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Sample records for roughened silver electrodes

  1. Specific adsorption of halide and pseudohalide ions at electrochemically roughened versus smooth silver-aqueous interfaces

    NASA Astrophysics Data System (ADS)

    Hupp, Joseph T.; Larkin, D.; Weaver, Michael J.

    1983-02-01

    The differential capacitance of electrochemically roughened silver surfaces in mixed perchlorate electrolytes containing chloride, bromide, iodide, thiocyanate, or azide anions has been measured as a function of electrode potential and anion concentration. These results are compared with corresponding data for electropolished silver in order to ascertain the influence of surface roughening on the double-layer structure and composition of polycrystalline silver-aqueous interfaces. The surface concentrations of specifically adsorbed anions were obtained from these capacitance-potential data using a "Hurwitz-Parsons" type of analysis. Although electrochemical roughening by means of a conventional oxidation-reduction cycle in chloride media is a prerequisite to the appearance of Surface-Enhanced Raman Scattering (SERS) for these adsorbates, it yields only moderate (ca. 1.5- to 2-fold) increases in the actual surface area and has a relatively minor effect on their average surface concentration. However, roughening does induce noticeable changes in the morphology of the capacitance-potential curves which are traced to alterations in the surface-crystallite structure. Comparisons between the potential dependence of SERS with corresponding capacitance-potential data indicate that anion coverages close to a monolayer are necessary for stable SERS. This is attributed to the stabilization of Raman-active silver clusters by surrounding adsorbed anions.

  2. Investigating the interfacial properties of electrochemically roughened platinum electrodes for neural stimulation.

    PubMed

    Weremfo, Alexander; Carter, Paul; Hibbert, D Brynn; Zhao, Chuan

    2015-03-01

    Platinum electrodes have been electrochemically roughened (roughness factors up to 430) and evaluated for use as neural stimulation electrodes. The roughened electrodes show superior interfacial properties with increasing surface roughness. The roughened electrode (fR = 250) has a charge injection limit of 1.0 mC cm(-2) (400 μs pulse width), which is superior to that of titanium nitride (0.87 mC cm(-2)) but comparable to that of carbon nanotubes (1.0-1.6 mC cm(-2)). The surface roughness can also be optimized for different neural stimulation applications based on the available charge density at a particular pulse width of stimulation. The roughened platinum electrodes demonstrated good mechanical stability under harsh ultrasonication and electrochemical stability under continuous biphasic stimulation, indicating the potential of this biological interface to be safe and stable. PMID:25669232

  3. Surface-enhanced resonance hyper-Raman scattering and surface-enhanced resonance Raman scattering of dyes adsorbed on silver electrode and silver colloid: a comparison study

    NASA Astrophysics Data System (ADS)

    Li, Wu-Hu; Li, Xiao-Yuan; Yu, Nai-Teng

    1999-10-01

    Surface-enhanced resonance hyper-Raman scattering (SERHRS) and surface-enhanced resonance Raman scattering (SERRS) of three dyes, rhodamine 6G, crystal violet and basic fuchsin, are studied comparatively on electrochemically roughened silver electrode and silver colloid, respectively. All three dyes show a better SERHRS efficiency on the silver colloid than on the silver electrode, a phenomenon just opposite to what we have recently observed for pyridine and pyrazine [Chem. Phys. Lett. 305 (1999) 303]. These results suggest that the efficiency of SEHRS depends not only on the active surfaces employed (colloidal metals versus roughened electrodes) but also on the types of the adsorbed molecules.

  4. Large-scale controlled fabrication of highly roughened flower-like silver nanostructures in liquid crystalline phase

    PubMed Central

    Yang, Chengliang; Xiang, Xiangjun; Zhang, Ying; Peng, Zenghui; Cao, Zhaoliang; Wang, Junlin; Xuan, Li

    2015-01-01

    Large-scale controllable fabrication of highly roughened flower-like silver nanostructures is demonstrated experimentally via electrodeposition in the liquid crystalline phase. Different sizes of silver flowers are fabricated by adjusting the deposition time and the concentration of the silver nitrate solution. The density of the silver flowers in the sample is also controllable in this work. The flower-like silver nanostructures can serve as effective surface-enhanced Raman scattering and surface-enhanced fluorescence substrates because of their local surface plasmon resonance, and they may have applications in photoluminescence and catalysis. This liquid crystalline phase is used as a soft template for fabricating flower-like silver nanostructures for the first time, and this approach is suitable for large-scale uniform fabrication up to several centimetres. PMID:26216669

  5. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  6. Surface-enhanced Raman spectroscopy of surfactants on silver electrodes

    SciTech Connect

    Sun, Soncheng; Birke, R.L.; Lombardi, J.R. )

    1990-03-08

    Surface-enhanced Raman spectroscopy (SERS) has been used to study different kinds of surfactants (cationic, anionic, and nonionic surfactants) adsorbed on a roughened Ag electrode. Spectral assignments are made for the SERS spectrum of cetylpyridinium chloride (CPC), and it is shown that the molecule is oriented with its pyridinium ring end-on at the electrode surface at potentials positive to the point of zero charge (pzc) on Ag.

  7. Failure of silver nanowire transparent electrodes under current flow

    PubMed Central

    2013-01-01

    Silver nanowire transparent electrodes have received much attention as a replacement for indium tin oxide, particularly in organic solar cells. In this paper, we show that when silver nanowire electrodes conduct current at levels encountered in organic solar cells, the electrodes can fail in as little as 2 days. Electrode failure is caused by Joule heating which causes the nanowires to breakup and thus create an electrical discontinuity in the nanowire film. More heat is created, and thus failure occurs sooner, in more resistive electrodes and at higher current densities. Suggestions to improve the stability of silver nanowire electrodes are given. PMID:23680014

  8. Silver electrodes for reversible oxygen sensor applications

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We report a single oxygen atomic sensor based on a scanning tunneling microscope break-junction (STM-BJ) technique by using silver electrodes at room temperature. The oxygen concentration was adjusted with argon gas in a glove box. An oxygen atom was inserted in the gap of the Ag electrodes after the Ag metal point contact had been ruptured during stretching of the Ag atomic junctions by moving a piezo. We successfully measured the conductance of a single oxygen atom by forming a series with the Ag contact, Ag-O-Ag bond. We found that the probability of Ag-O-Ag junction formation increased with increasing oxygen concentration. Furthermore, we observed that the peak height in the oxygen conductance histogram was changed reversibly depending on the oxygen concentration in a glove box. It confirms that our STM-BJ can be used for atomic sensor applications in the future.

  9. Preparation of thin film silver fluoride electrodes from constituent elements

    NASA Technical Reports Server (NTRS)

    Odonnell, P. M.

    1972-01-01

    The feasibility of preparing thin-film metal fluoride electrodes from the elemental constituents has been demonstrated. Silver fluoride cathodes were prepared by deposition of silver on a conducting graphite substrate followed by fluorination under controlled conditions using elemental fluorine. The resulting electrodes were of high purity, and the variables such as size, shape, and thickness were easily controlled.

  10. Life capability of the silver electrode in alkaline electrochemical cells

    NASA Technical Reports Server (NTRS)

    Frank, H. A.

    1976-01-01

    Estimates of silver electrode degradation rates were made by comparing the recently measured capacities with the reported early life capacities. Chemical analyses were carried out to determine the extent of silver loss from the electrode and its distribution throughout the cell components. The results established that the silver electrode is very stable when stored at reduced temperatures in the range of 0 to -51 C, in which it exhibits a permanent degradation in capacity of 0.5%/year. The results also indicated that the silver electrode is not quite as stable when operated and stored at room temperature, where it exhibits permanent degradation in the range of 3% to 14%/year. These results were employed in predicting the life capability of the proposed new Ag-H2 cell and also in assessing the merits of employing silver electrodes in long-life probe batteries.

  11. A nano-silver enzyme electrode for organophosphorus pesticide detection.

    PubMed

    Zheng, Qiqi; Yu, Yonghua; Fan, Kai; Ji, Feng; Wu, Jian; Ying, Yibin

    2016-08-01

    A nano-silver electrode immobilizing acetylcholinesterase (AChE) for the detection of organophosphorus (OPPs) pesticides is reported. Scanning electron microscopy (SEM) was used to characterize the surface structure of two kinds of electrodes fabricated with different sizes of silver powders and the interface between chitosan layer and nano-silver powder layer. Cyclic voltammetry was carried out to characterize the response of silver/chitosan electrode in the absence and in the presence of thiocholine (TCh). It was also used to evaluate the insulativity of the chitosan layer. An amperometric method was performed to measure the response of the electrode to TCh, which is the product of the enzymatic reaction for detecting organophosphorus pesticides indirectly. Although there are many kinds of nanoparticles, silver was chosen for its internal advantage in detecting TCh at low potential without further modification. The result shows nano-silver powder has better performance than usual silver powder, and the limit of detection of paraoxon is 4 ppb under optimized conditions. One percent (w/v) chitosan solution was used as binder for the immobilization of nano-silver powder and AChE, which made it possible for independent electrode fabrication at room temperature, whereas 3% (w/v) chitosan solution was used as insulating compound for controlling the electrode area. Unlike traditional organic insulating ink, chitosan is safe and environmentally friendly, and it is used as insulating material for the first time. The flexible nano-silver/AChE/chitosan electrode was evaluated in Chinese chives and cabbage, and the recoveries of standard addition were 105.11 and 96.41%, respectively. Owing to the antibacterial property of nano-silver and the biocompatibility, safety, and biodegradability of chitosan, the proposed method is safe, facile, environmentally friendly, and has great potential in organophosphorus pesticide detection for food safety. Graphical Abstract Current

  12. Rolling silver nanowire electrodes: simultaneously addressing adhesion, roughness, and conductivity.

    PubMed

    Hauger, Tate C; Al-Rafia, S M Ibrahim; Buriak, Jillian M

    2013-12-11

    Silver nanowire mesh electrodes represent a possible mass-manufacturable route toward transparent and flexible electrodes for plastic-based electronics such as organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), and others. Here we describe a route that is based upon spray-coated silver nanowire meshes on polyethylene terephthalate (PET) sheets that are treated with a straightforward combination of heat and pressure to generate electrodes that have low sheet resistance, good optical transmission, that are topologically flat, and adhere well to the PET substrate. The silver nanowire meshes were prepared by spray-coating a solution of silver nanowires onto PET, in air at slightly elevated temperatures. The as-prepared silver nanowire electrodes are highly resistive due to the poor contact between the individual silver nanowires. Light pressure applied with a stainless steel rod, rolled over the as-sprayed silver nanowire meshes on PET with a speed of 10 cm s(-1) and a pressure of 50 psi, results in silver nanowire mesh arrays with sheet resistances of less than 20 Ω/□. Bending of these rolled nanowire meshes on PET with different radii of curvature, from 50 to 0.625 mm, showed no degradation of the conductivity of the electrodes, as shown by the constant sheet resistance before and after bending. Repeated bending (100 times) around a rod with a radius of curvature of 1 mm also showed no increase in the sheet resistance, demonstrating good adherence and no signs of delamination of the nanowire mesh array. The diffuse and direct transmittance of the silver nanowires (both rolled and as-sprayed) was measured for wavelengths from 350 to 1200 nm, and the diffuse transmission was similar to that of the PET substrate; the direct transmission decreases by about 7-8%. The silver nanowires were then incorporated into OPV devices with the following architecture: transparent electrode/PEDOT:PSS/P3HT:PC61BM/LiF/Al. While slightly lower in efficiency than the

  13. Aging in chemically prepared divalent silver oxide electrodes for silver/zinc reserve batteries

    NASA Astrophysics Data System (ADS)

    Smith, David F.; Brown, Curtis

    The instability of silver(II) oxide electrodes used in silver/zinc reserve batteries is the well known cause of capacity loss and delayed activation in reserve batteries after they are stored in the dry, unactivated state for extended periods of time. Metal contaminants in sintered/electroformed electrodes destabilize the oxide and the solid state reaction between AgO and elemental silver results in the formation of the lower capacity monovalent oxide Ag 2O. Chemically prepared (CP) AgO can be used to avoid the metal contaminants and to minimize the interfacial contact area between AgO and Ag, thus minimizing the affects of aging on the electrodes. Electrodes were fabricated with CP AgO and polytetrafluoroethylene (PTFE) binder and expanded silver metal current collectors. Experimentally, both electrode active material compacts (AgO and binder only) and electrodes complete with AgO/binder and silver current collector were tested to evaluate the influence of the current collector on aging. The electrode samples were discharged at a constant rate of 50 mA cm -2 before and after storage at 60°C for 21 days as well as after storage at room ambient temperature conditions for 91 months. The results indicate that the affects of aging upon the AgO/binder compacts are insignificant for long term storage at room temperature. However, thermally accelerated aging at high temperature (60°C) affects both transient and stabilized load voltage as well as capacity. In terms of capacity, the AgO/binder mix itself looses about 5% capacity after 21 days dry storage at 60°C while electrodes complete with current collector loose about 8%. The 60% increase in capacity loss is attributed to the solid state reaction between AgO and elemental silver.

  14. Highly Robust Silver Nanowire Network for Transparent Electrode.

    PubMed

    Song, Tze-Bin; Rim, You Seung; Liu, Fengmin; Bob, Brion; Ye, Shenglin; Hsieh, Yao-Tsung; Yang, Yang

    2015-11-11

    Solution-processed silver nanowire networks are one of the promising candidates to replace a traditional indium tin oxide as next-generation transparent and flexible electrodes due to their ease of processing, moderate flexibility, high transparency, and low sheet resistance. To date, however, high stability of the nanowire networks remains a major challenge because the long-term usages of these electrodes are limited by their poor thermal and chemical stabilities. Existing methods for addressing this challenge mainly focus on protecting the nanowire network with additional layers that require vacuum processes, which can lead to an increment in manufacturing cost. Here, we report a straightforward strategy of a sol-gel processing as a fast and robust way to improve the stabilities of silver nanowires. Compared with reported nanoparticles embedded in nanowire networks, better thermal and chemical stabilities are achieved via sol-gel coating of TiO2 over the silver nanowire networks. The conformal surface coverage suppressed surface diffusion of silver atoms and prevented chemical corrosion from the environment. These results highlight the important role of the functional layer in providing better thermal and chemical stabilities along with improved electrical properties and mechanical robustness. The silver nanowire/TiO2 composite electrodes were applied as the source and drain electrodes for In2O3 thin-film transistors (TFTs) and the devices exhibited improved electrical performance annealed at 300 °C without the degradation of the electrodes. These key findings not only demonstrated a general and effective method to improve the thermal and chemical stabilities of metal nanowire networks but also provided a basic guideline toward rational design of highly efficient and robust composite electrodes. PMID:26488682

  15. Selective growth and integration of silver nanoparticles on silver nanowires at room conditions for transparent nano-network electrode.

    PubMed

    Lu, Haifei; Zhang, Di; Ren, Xingang; Liu, Jian; Choy, Wallace C H

    2014-10-28

    Recently, metal nanowires have received great research interests due to their potential as next-generation flexible transparent electrodes. While great efforts have been devoted to develop enabling nanowire electrodes, reduced contact resistance of the metal nanowires and improved electrical stability under continuous bias operation are key issues for practical applications. Here, we propose and demonstrate an approach through a low-cost, robust, room temperature and room atmosphere process to fabricate a conductive silver nano-network comprising silver nanowires and silver nanoparticles. To be more specific, silver nanoparticles are selectively grown and chemically integrated in situ at the junction where silver nanowires meet. The site-selective growth of silver nanoparticles is achieved by a plasmon-induced chemical reaction using a simple light source at very low optical power density. Compared to silver nanowire electrodes without chemical treatment, we observe tremendous conductivity improvement in our silver nano-networks, while the loss in optical transmission is negligible. Furthermore, the silver nano-networks exhibit superior electrical stability under continuous bias operation compared to silver nanowire electrodes formed by thermal annealing. Interestingly, our silver nano-network is readily peeled off in water, which can be easily transferred to other substrates and devices for versatile applications. We demonstrate the feasibly transferrable silver conductive nano-network as the top electrode in organic solar cells. Consequently, the transparent and conductive silver nano-networks formed by our approach would be an excellent candidate for various applications in optoelectronics and electronics. PMID:25285984

  16. Silver-silver sulfate reference electrodes for use in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Ruetschi, Paul

    Electrochemical properties of silver-silver sulfate reference electrodes for lead-acid batteries are described, and the following possible applications discussed: Determination of individual capacities of positive and negative plates. Monitoring individual electrode behavior during deep discharge and cell reversal. Optimization charge or discharge parameters, by controlling the current such that pre-determined limits of positive or negative half-cell potential are respected. Observation of acid concentration differences, for example due to acid stratification, by measuring diffusion potentials (concentration-cell voltages). Detection of defective cells, and defective plate sets, in a string of cells, at the end of their service life. Silver-silver sulfate reference electrodes, permanently installed in lead-acid cells, may be a means to improve battery management, and therewith to improve reliability and service life. In vented batteries, reference electrodes may be used to limit positive plate polarization during charge, or float-charge. Limiting the positive half-cell potential to an upper, pre-set value would permit to keep anodic corrosion as low as possible. During cycling, discharge could be terminated when the half-cell potential of the positive electrode has dropped to a pre-set limit. This would prevent excessive discharge of the positive electrodes, which could result in an improvement of cycle life. In valve-regulated batteries, reference electrodes may be used to adjust float-charge conditions such as to assure sufficient cathodic polarization of the negative electrodes, in order to avoid sulfation. The use of such reference electrodes could be beneficial particularly in multi-cell batteries, with overall voltages above 12 V, operated in a partial-state-of-charge.

  17. Inkjet printed fractal-connected electrodes with silver nanoparticle ink.

    PubMed

    Vaseem, Mohammad; Lee, Kil Mok; Hong, A-Ra; Hahn, Yoon-Bong

    2012-06-27

    The development of a simple and reliable method for nanoparticles-based ink in an aqueous solution is still a challenge for its inkjet printing application. Herein, we demonstrate the inkjet printing of fractal-aggregated silver (Ag) electrode lines on substrates. Spherical, monodisperse Ag nanoparticles have been synthesized using silver nitrate as a precursor, ethylene glycol as a reducing agent, and polyvinyl pyrrollidone as a capping agent. As-synthesized pure Ag nanoparticles were well dispersed in water-ethylene glycol mixture, which was directly used as an ink for inkjet printing. Using this ink, the Ag electrodes of fractal-connected lines were printed on Si/SiO2, glass, and polymer substrates. The fractal-connected Ag lines were attributed to the diffusion-limited aggregation of Ag nanoparticles and the effect of annealing on conductivity was also examined. PMID:22670766

  18. Synthetic silver oxide and mercury-free zinc electrodes for silver-zinc reserve batteries

    NASA Astrophysics Data System (ADS)

    Smith, David F.; Gucinski, James A.

    Reserve activated silver oxide-zinc cells were constructed with synthetic silver oxide (Ag 2O) electrodes with Pb-treated zinc electrodes produced by a non-electrolytic process. The cells were tested before and after thermally accelerated aging. At discharge rates up to 80 mA cm -2, the discharge was limited by the Ag 2O electrode, with a coulombic efficiency between 89-99%. At higher rates, the cells are apparently zinc-limited. Test cells were artificially aged at 90°C for 19 h and discharged at 21°C at 80 mA cm -2. No capacity loss was measured, but a delayed activation rise time was noted (192 ms fresh vs. 567 ms aged). The delay is thought to be caused by zinc passivation due to the outgassing of cell materials.

  19. Ionic polymer metal composites with polypyrrole-silver electrodes

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Grillo, A.; Porfiri, M.

    2015-03-01

    Ionic polymer metal composites (IPMCs) are a class of soft active materials that are finding increasing application in robotics, environmental sensing, and energy harvesting. In this letter, we demonstrate the fabrication of IPMCs via in-situ photoinduced polymerization of polypyrrole-silver electrodes on an ionomeric membrane. The composition, morphology, and sheet resistance of the electrodes are extensively characterized through a range of experimental techniques. We experimentally investigate IPMC electrochemistry through electrochemical impedance spectroscopy, and we propose a modified Randle's model to interpret the impedance spectrum. Finally, we demonstrate in-air dynamic actuation and sensing and assess IPMC performance against more established fabrication methods. Given the simplicity of the process and the short time required for the formation of the electrodes, we envision the application of our technique in the development of a rapid prototyping technology for IPMCs.

  20. Investigations on silver/polyaniline electrodes for electrochemical supercapacitors.

    PubMed

    Patil, Dipali S; Shaikh, J S; Pawar, S A; Devan, R S; Ma, Y R; Moholkar, A V; Kim, J H; Kalubarme, R S; Park, C J; Patil, P S

    2012-09-14

    Polyaniline (PANI) and silver doped polyaniline (Ag/PANI) thin films were deposited on stainless steel substrates by a dip coating technique. To study the effect of doping concentration of Ag on the specific capacitance of PANI the concentration of Ag was varied from 0.3 to 1.2 weight percent. Fourier transform-infrared and Fourier transform-Raman spectroscopy, and energy dispersion X-ray techniques were used for the phase identification and determination of the doping content in the PANI films, respectively. The surface morphology of the films was examined by Field Emission Scanning Electron Microscopy, which revealed a nanofiber like structure for PANI and nanofibers with bright spots of Ag particles for the Ag/PANI films. There was decrease in the room temperature electrical resistivity of the Ag/PANI films of the order of 10(2) with increasing Ag concentration. The supercapacitive behavior of the electrodes was tested in a three electrode system using 1.0 M H(2)SO(4) electrolyte. The specific capacitance increased from 285 F g(-1) (for PANI) to 512 F g(-1) for Ag/PANI at 0.9 weight percent doping of Ag, owing to the synergic effect of PANI and silver nanoparticles. This work demonstrates a simple strategy of improving the specific capacitance of polymer electrodes and may also be easily adopted for other dopants. PMID:22850931

  1. Amperometric Sensor Used for Determination of Thiocyanate with a Silver Nanoparticles Modified Electrode

    PubMed Central

    Wang, Guang-Feng; Li, Mao-Guo; Gao, Ying-Chun; Fang, Bin

    2004-01-01

    A novel electrode modified with silver nanoparticles was fabricated. It is found that the reducibility of silver nanoparticles is higher than for bulk silver by comparing a silver nanoparticles modified electrode with a silver micro-disk electrode. When SCN- was added, a new oxidation peak occurred and the anodic peak current of silver nanoparticles decreased. The new anodic peak current is proportional to the thiocyanate concentration in the range of 5.0×10-7∼4.0×10-4 mol/L in pH 6.0 NaH2PO4-Na2HPO4 buffer solutions (PBS). The detection limit (S/N=3) is 4×10-8 mol/L. This method has been applied to the determination of saliva (smoker and non-smoker).

  2. Operando studies of all-vanadium flow batteries: Easy-to-make reference electrode based on silver-silver sulfate

    NASA Astrophysics Data System (ADS)

    Ventosa, Edgar; Skoumal, Marcel; Vázquez, Francisco Javier; Flox, Cristina; Morante, Joan Ramon

    2014-12-01

    In-depth evaluation of the electrochemical performance of all-vanadium redox flow batteries (VRFBs) under operando conditions requires the insertion of a reliable reference electrode in the battery cell. In this work, an easy-to-make reference electrode based on silver-silver sulfate is proposed and described for VRFBs. The relevance and feasibility of the information obtained by inserting the reference electrode is illustrated with the study of ammoxidized graphite felts. In this case, we show that the kinetic of the electrochemical reaction VO2+/VO2+ is slower than that of V2+/V3+ at the electrode. While the slow kinetics at the positive electrode limits the voltage efficiency, the operating potential of the negative electrode, which is outside the stability widow of water, reduces the coulombic efficiency due to the hydrogen evolution.

  3. Modified silver nanowire transparent electrodes with exceptional stability against oxidation

    NASA Astrophysics Data System (ADS)

    Idier, J.; Neri, W.; Labrugère, C.; Ly, I.; Poulin, P.; Backov, R.

    2016-03-01

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh3) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh3. The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc/σ op. This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc/σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones.

  4. Modified silver nanowire transparent electrodes with exceptional stability against oxidation.

    PubMed

    Idier, J; Neri, W; Labrugère, C; Ly, I; Poulin, P; Backov, R

    2016-03-11

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh3) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh3. The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc/σ op. This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc/σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones. PMID:26866415

  5. Screen printed silver top electrode for efficient inverted organic solar cells

    SciTech Connect

    Kim, Junwoo; Duraisamy, Navaneethan; Lee, Taik-Min; Kim, Inyoung; Choi, Kyung-Hyun

    2015-10-15

    Highlights: • Screen printing of silver pattern. • X-ray diffraction pattern confirmed the face centered cubic structure of silver. • Uniform surface morphology of silver pattern with sheet resistance of 0.06 Ω/sq. • The power conversion efficiency of fabricated solar cell is found to be 2.58%. - Abstract: The present work is mainly focused on replacement of the vacuum process for top electrode fabrication in organic solar cells. Silver top electrode deposited through solution based screen printing on pre-deposited polymeric thin film. The solution based printing technology provides uniform top electrode without damaging the underlying organic layers. The surface crystallinity and surface morphology of silver top electrode are examined through X-ray diffraction, field-emission scanning electron microscope and atomic force microscope. The purity of silver is examined through X-ray energy dispersive spectroscopy. The top electrode exhibits face centered cubic structure with homogeneous morphology. The sheet resistance of top electrode is found to be 0.06 Ω/sq and an average pattern thickness of ∼15 μm. The power conversion efficiency is 2.58%. Our work demonstrates that the solution based screen printing is a significant role in the replacement of vacuum process for the fabrication of top electrode in organic solar cells.

  6. Roll to plate printed stretchable silver electrode using single walled carbon nanotube on elastomeric substrate.

    PubMed

    Jung, Minhun; Noh, Jinsoo; Kim, Junseok; Kim, Donghwan; Cho, Gyoujin

    2013-08-01

    Stretchable electronics may open new applications in display, sensors and actuators. To attain the stretchable electronics, the ink formulation should be compatible with elastomeric substrates. Here, we present the formulation of silver nanoparticles and single walled carbon nanotubes (SWNTs) for printing stretchable silver electrodes on the elastomeric substrates. Highly conductive stretchable electrodes can be printed directly on the poly(styrene-b-butadiene-b-styrene) (PSBS) substrates by roll to plate (R2P) gravure printer. During the stretching test, R2P printed silver based stretchable electrodes show the high conductivity of 1000 S cm(-1) at 0.27 wt% of SWNT loading. Furthermore, the resistance of the printed silver electrode was not changed up to 15% of tensile strain. PMID:23882805

  7. Electrochemical reclamation of silver from silver-plating wastewater using static cylinder electrodes and a pulsed electric field.

    PubMed

    Su, Yuan-Bo; Li, Qing-Biao; Wang, Yuan-Peng; Wang, Hai-Tao; Huang, Jia-le; Yang, Xin

    2009-10-30

    Silver was reclaimed from silver-plating wastewater by using a pulsed electric field (PEF) combined with static cylinder electrodes (SCE). The conditions that produced the maximal silver recovery rate (RR(Ag)) (99%) were as follows: average retention time of 10 min, interelectrode gap of 50mm, solution pH of 9.0, temperature of 45 degrees C, initial Ag(I) concentration of 1000 mg L(-1), PEF pulse frequency of 1200 Hz, current density of 5.0 A m(-2) and a pulse duty cycle of 60%. Compared with the conventional direct current (DC) technology, the PEF process exhibited improvements in the silver recovery rate (RR(Ag)), total energy consumption (TEC) and physical properties of the silver deposits, especially for low Ag(I) concentrations, for example, from 500 to 1000 mg L(-1). For an initial Ag(I) concentration of 500 mg L(-1), the PEF process produced an RR(Ag) of up to 99%, and the TEC was 4.56 kWh (kg Ag)(-1). In comparison, the RR(Ag) and TEC were 90% and 5.66 kWh (kg Ag)(-1), respectively, in the DC process. The results of SEM observation and XRD analysis indicated that the silver deposits formed by the PEF process were smaller, denser, and of a higher purity than those produced by the DC process. Therefore, the presented method was effective for reclaiming silver from silver-plating wastewater. PMID:19545945

  8. Development of coated-wire silver ion selective electrodes on paper using conductive films of silver nanoparticles.

    PubMed

    Janrungroatsakul, Wanwisa; Lertvachirapaiboon, Chutiparn; Ngeontae, Wittaya; Aeungmaitrepirom, Wanlapa; Chailapakul, Orawon; Ekgasit, Sanong; Tuntulani, Thawatchai

    2013-11-21

    Films of silver nanoparticles are used for the first time as an electrical conductor and ion-to-electron transducer to fabricate coated-wire ion selective electrodes (ISEs) on paper. The film of nano silver ink (nano silver film), synthesized from the reduction of AgNO3 by NaBH4, was screen printed on paper. Transmission electron microscopy showed that the synthesized silver nanoparticles (AgNPs) possessed a spherical shape with diameter ca. 5 nm. Energy-dispersive X-ray spectroscopy supported the purity and good stability of the synthesized AgNPs. Nano silver films were sintered at room temperature, 100 °C and 200 °C. Upon increasing the sintering temperature, atomic force microscopy showed that the size of AgNPs of nano silver films increased, but the sheet resistivity decreased. Silver ISEs were then fabricated from nano silver films and o-NPOE-plasticized polymeric membranes containing benzothiazolyl calix[4]arene () as ionophore and KTpClPB as anionic site. The performance of the developed Ag-ISEs was investigated by potentiometric measurements, potentiometric water layer tests, current reversal chronopotentiometry and electrochemical impedance spectroscopy. The coated-wire electrode fabricated from the nano silver film sintering at room temperature showed the best characteristics of Ag-ISEs giving a near Nernstian response slope of 59.7 ± 1.0 mV per decade, 10(-6) to 10(-2) M linear range, detection limit of 4.5 × 10(-7) M, long-term potential stability and good reversibility. PMID:24071789

  9. Evidence for the conformational rigidity of triplex d(C +T) 8-d(AG) 8·d(CT) 8 on silver electrode revealed by Fourier transform Raman scattering studies

    NASA Astrophysics Data System (ADS)

    Fang, Ye; Bai, Chunli; Wang, Ting; Zhong, Faping; Tang, Youqi; Lin, S. B.; Kan, Lou-sing

    1996-03-01

    Fourier transform surface enhanced Raman scattering spectroscopy (FT-SERS) has been first applied to characterize the triple stranded helix d(C +T) 8-d(AG) 8·d(CT) 8 (pH 4.5) (triplex) and its corresponding double-stranded helix d(AG) 8·d(CT) 8 (pH 7.0) (duplex) at an ex situ roughened silver electrode polarized at between 0.0 and -1.0 V vs. {Ag}/{AgCl}. The triplex adsorbed on the silver electrode yields five intense and one weak SERS bands located at 241, 839, 1189, 1293, 1643, and 1530 cm -1, respectively. These bands are not seen in the FT-SERS spectrum of the duplex, which showed a pattern similar to that of an oligo-DNA duplex observed by Koglin and Sequaries (Top. Curr. Chem., 134 (1989) 1). In the case of the triplex, the occurrence of the 839 cm -1 band with concomitant disappearance of the adsorbed adenine ring-breathing band at 734 cm -1 of the duplex indicates that the helical structure of the triplex near the surface of the silver electrode is well preserved and exhibits conformational rigidity. We observed a desorption process of the triplex from the silver electrode when the electrode approached -0.9 V (potential of zero charge of the triplex) vs. {Ag}/{AgCl}. This indicates that the highly negatively charged triplex shows a more favorable absorption on a highly positively charged silver surface. The structure of the triplex has also been studied by Fourier transform infrared (FTIR) and Raman spectroscopy. The vibrational spectra obtained clearly revealed that the conformation of the sugar moiety of the purine strand and one pyrimidine strand in the triplex is C 2'-endo/anti, whereas that of the other pyrimidine strand is C 3'-endo/anti.

  10. Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide.

    PubMed

    Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

    2012-12-01

    Solution-processable silver nanowire-reduced graphene oxide (AgNW-rGO) hybrid transparent electrode was prepared in order to replace conventional ITO transparent electrode. AgNW-rGO hybrid transparent electrode exhibited high optical transmittance and low sheet resistance, which is comparable to ITO transparent electrode. In addition, it was found that AgNW-rGO hybrid transparent electrode exhibited highly enhanced thermal oxidation and chemical stabilities due to excellent gas-barrier property of rGO passivation layer onto AgNW film. Furthermore, the organic solar cells with AgNW-rGO hybrid transparent electrode showed good photovoltaic behavior as much as solar cells with AgNW transparent electrode. It is expected that AgNW-rGO hybrid transparent electrode can be used as a key component in various optoelectronic application such as display panels, touch screen panels, and solar cells. PMID:23206541

  11. Embroidered Electrode with Silver/Titanium Coating for Long-Term ECG Monitoring

    PubMed Central

    Weder, Markus; Hegemann, Dirk; Amberg, Martin; Hess, Markus; Boesel, Luciano F.; Abächerli, Roger; Meyer, Veronika R.; Rossi, René M.

    2015-01-01

    For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irritating, but in addition they must deliver leads without artifacts even if the skin is dry and the body is moving. Today's adhesive conducting gel electrodes are not suitable for such applications. We have developed an embroidered textile electrode from polyethylene terephthalate yarn which is plasma-coated with silver for electrical conductivity and with an ultra-thin titanium layer on top for passivation. Two of these electrodes are embedded into a breast belt. They are moisturized with a very low amount of water vapor from an integrated reservoir. The combination of silver, titanium and water vapor results in an excellent electrode chemistry. With this belt the long-time monitoring of electrocardiography (ECG) is possible at rest as well as when the patient is moving. PMID:25599424

  12. Embroidered electrode with silver/titanium coating for long-term ECG monitoring.

    PubMed

    Weder, Markus; Hegemann, Dirk; Amberg, Martin; Hess, Markus; Boesel, Luciano F; Abächerli, Roger; Meyer, Veronika R; Rossi, René M

    2015-01-01

    For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irritating, but in addition they must deliver leads without artifacts even if the skin is dry and the body is moving. Today's adhesive conducting gel electrodes are not suitable for such applications. We have developed an embroidered textile electrode from polyethylene terephthalate yarn which is plasma-coated with silver for electrical conductivity and with an ultra-thin titanium layer on top for passivation. Two of these electrodes are embedded into a breast belt. They are moisturized with a very low amount of water vapor from an integrated reservoir. The combination of silver, titanium and water vapor results in an excellent electrode chemistry. With this belt the long-time monitoring of electrocardiography (ECG) is possible at rest as well as when the patient is moving. PMID:25599424

  13. Nanostructured electrochromic films by inkjet printing on large area and flexible transparent silver electrodes

    NASA Astrophysics Data System (ADS)

    Layani, Michael; Darmawan, Peter; Foo, Wan Ling; Liu, Liang; Kamyshny, Alexander; Mandler, Daniel; Magdassi, Schlomo; Lee, Pooi See

    2014-04-01

    Printed electrochromic flexible films were obtained by combining transparent silver grid electrodes formed by self-assembly and inkjet printed WO3 nanoparticles. Concentrated dispersions of WO3 nanoparticles were inkjet printed on transparent plastic silver grid electrodes with a high transparency of 83% in the spectral range of 400-800 nm, and a low sheet resistance in the range of 1-5 Ω sq-1. These electrodes were used for electrochromic applications for the first time. The resultant patterned nanostructured electrochromic films maintained their coloring and bleaching performance after bending of the flexible films.Printed electrochromic flexible films were obtained by combining transparent silver grid electrodes formed by self-assembly and inkjet printed WO3 nanoparticles. Concentrated dispersions of WO3 nanoparticles were inkjet printed on transparent plastic silver grid electrodes with a high transparency of 83% in the spectral range of 400-800 nm, and a low sheet resistance in the range of 1-5 Ω sq-1. These electrodes were used for electrochromic applications for the first time. The resultant patterned nanostructured electrochromic films maintained their coloring and bleaching performance after bending of the flexible films. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06890k

  14. Flow Synthesis of Silver Nanowires for Semitransparent Solar Cell Electrodes: A Life Cycle Perspective.

    PubMed

    Espinosa, Nieves; Søndergaard, Roar R; Jørgensen, Mikkel; Krebs, Frederik C

    2016-04-21

    Silver nanowires (AgNWs) were prepared on a 5 g scale using either the well-known batch synthesis following the polyol method or a new flow synthesis method. The AgNWs were employed as semitransparent electrode materials in organic photovoltaics and compared to traditional printed silver electrodes based on micron sized silver flakes using life cycle analysis and environmental impact analysis methods. The life cycle analysis of AgNWs confirms that they provide an avenue to low-impact semitransparent electrodes. We find that the benefit of AgNWs in terms of embodied energy is less pronounced than generally assumed but that the toxicological and environmental benefits are significant. PMID:26969912

  15. Investigation of spray-coated silver-microparticle electrodes for ionic electroactive polymer actuators

    NASA Astrophysics Data System (ADS)

    Meis, Catherine; Hashemi, Nastaran; Montazami, Reza

    2014-04-01

    We have employed the easy-to-scale-up method of spray-coating in combination with layer-by-layer self-assembly technique to fabricate ionic electroactive polymer actuators (IEAPAs). IEAPAs with spray-coated silver microparticle electrodes demonstrate enhanced strain and response time when compared to nearly identical, optimized conventional IEAPA with gold leaf electrodes. The results demonstrate that strain of these IEAPAs increases with the decrease of thickness of the outer silver microparticle electrodes. In addition, the response time of the actuators at frequencies of 1 and 10 Hz improves compared to optimized conventionally fabricated IEAPA. It was found that samples consisting of spray-coated silver electrodes can charge up to ˜3 times faster than conventional actuators at 1 Hz frequency. Faster charging/discharging results in higher mobility of ions within the actuator and thus, faster actuation. Given the relatively large thickness of the silver microparticle electrodes (˜50× gold leaf), similar strain was observed due to the lower Young's modulus of spray-coated layers compared to that of bulk material.

  16. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    SciTech Connect

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-08-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

  17. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    SciTech Connect

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-10-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

  18. Anodic stripping voltammetry with graphite felt electrodes for the trace analysis of silver.

    PubMed

    Davies, Trevor J

    2016-08-01

    Graphite felt (GF) is a mass produced porous carbon electrode material commonly used in redox flow batteries. Previous studies have suggested GF may have valuable applications in electroanalysis as a low cost disposable carbon electrode material, although most GF sensors have used flow cell arrangements. In this work, an elegant wetting technique is employed that allows GF electrodes to be used in quiescent solution to detect trace levels of silver in water via anodic stripping voltammetry. GF electrodes display good repeatability and a limit of detection of 25 nM of Ag(+) in 0.1 M HNO3, with a linear range spanning two orders of magnitude. This compares to a value of around 140 nM when using conventional carbon electrodes. Combined with their low cost and disposable nature, the results suggest GF electrodes can make a valuable contribution to electroanalysis. PMID:27276994

  19. Laser Processed Silver Nanowire Network Transparent Electrodes for Novel Electronic Devices

    NASA Astrophysics Data System (ADS)

    Spechler, Joshua Allen

    Silver nanowire network transparent conducting layers are poised to make headway into a space previously dominated by transparent conducting oxides due to the promise of a flexible, scaleable, lab-atmosphere processable alternative. However, there are many challenges standing in the way between research scale use and consumer technology scale adaptation of this technology. In this thesis we will explore many, and overcome a few of these challenges. We will address the poor conductivity at the narrow nanowire-nanowire junction points in the network by developing a laser based process to weld nanowires together on a microscopic scale. We address the need for a comparative metric for transparent conductors in general, by taking a device level rather than a component level view of these layers. We also address the mechanical, physical, and thermal limitations to the silver nanowire networks by making composites from materials including a colorless polyimide and titania sol-gel. Additionally, we verify our findings by integrating these processes into devices. Studying a hybrid organic/inorganic heterojunction photovoltaic device we show the benefits of a laser processed electrode. Green phosphorescent organic light emitting diodes fabricated on a solution phase processed silver nanowire based electrode show favorable device metrics compared to a conductive oxide electrode based control. The work in this thesis is intended to push the adoption of silver nanowire networks to further allow new device architectures, and thereby new device applications.

  20. Embedded silver PDMS electrodes for single cell electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Yuan; Xu, Zhensong; Cachia, Mark A.; Nguyen, John; Zheng, Yi; Wang, Chen; Sun, Yu

    2016-09-01

    This paper presents a microfluidic device with wide channels and embedded AgPDMS electrodes for measuring the electrical properties of single cells. The work demonstrates the feasibility of using a large channel design and embedded electrodes for impedance spectroscopy to circumvent issues such as channel clogging and limited device re-usability. AgPDMS electrodes were formed on channel sidewalls for impedance detection and cell electrical properties measurement. Equivalent circuit models were used to interpret multi-frequency impedance data to quantify each cell’s cytoplasm conductivity and specific membrane capacitance. T24 cells were tested to validate the microfluidic system and modeling results. Comparisons were then made by measuring two leukemia cell lines (AML-2 and HL-60) which were found to have different cytoplasm conductivity values (0.29  ±  0.15 S m‑1 versus 0.47  ±  0.20 S m‑1) and specific membrane capacitance values (41  ±  25 mF m‑2 versus 55  ±  26 mF m‑2) when the cells were flown through the wide channel and measured by the AgPDMS electrodes.

  1. Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes

    NASA Astrophysics Data System (ADS)

    Stapleton, Andrew J.; Yambem, Soniya D.; Johns, Ashley H.; Afre, Rakesh A.; Ellis, Amanda V.; Shapter, Joe G.; Andersson, Gunther G.; Quinton, Jamie S.; Burn, Paul L.; Meredith, Paul; Lewis, David A.

    2015-04-01

    Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω-1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.

  2. Large Pulsed Electron Beam Welded Percolation Networks of Silver Nanowires for Transparent and Flexible Electrodes.

    PubMed

    Kim, Jisoo; Nam, Yun Seok; Song, Myoung Hoon; Park, Hyung Wook

    2016-08-17

    Mechanical properties of transparent electrodes, including flexibility, are important in flexible electronics for sustaining electrical conductivity under bending with small radius of curvature. Low contact resistance of junctions in metal nanowire percolation networks is the most important factor to produce electrodes with excellent optical, electrical and mechanical performance. Here, we report the fabrication of welded silver nanowire percolation networks using large pulsed electron beam (LPEB) irradiation as a welding process of silver nanowires (AgNWs). It results in modification of electrical and mechanical properties because of the low contact resistance at welded junctions. Consequently, the flexible and transparent AgNW electrodes fabricated by LPEB irradiation showed lower sheet resistance of 12.63 Ω sq(-1) at high transmittance of 93% (at 550 nm), and superb mechanical flexibility, compared with other AgNW electrodes prepared by thermal treatement and without any treatment. Polymer light-emitting diodes (PLEDs) using AgNWs by LPEB irradiation were fabricated to confirm that the AgNW electrode by LPEB irradiation was able to become alternative to indium tin oxide (ITO) and they showed good device performance as a maximum luminous efficiency of 7.37 cd A(-1), and excellent mechanical flexibility under bending with small radius of curvature. PMID:27463783

  3. Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode

    NASA Astrophysics Data System (ADS)

    Solovyeva, Elena V.; Myund, Liubov A.; Denisova, Anna S.

    2015-10-01

    4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd2+ ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd2+ complex which desorption causes the loss of SERS signal.

  4. Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode.

    PubMed

    Solovyeva, Elena V; Myund, Liubov A; Denisova, Anna S

    2015-10-01

    4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd(2+) ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd(2+) complex which desorption causes the loss of SERS signal. PMID:25956332

  5. Silver nanowire/polyaniline composite transparent electrode with improved surface properties

    SciTech Connect

    Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai Kim, Sang-Ho

    2014-09-15

    Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

  6. Uniformly embedded silver nanomesh as highly bendable transparent conducting electrode

    NASA Astrophysics Data System (ADS)

    Choi, Hak-Jong; Choo, Soyoung; Jung, Pil-Hoon; Shin, Ju-Hyeon; Kim, Yang-Doo; Lee, Heon

    2015-02-01

    Ag-nanomesh-based highly bendable conducting electrodes are developed using a combination of metal nanotransfer printing and embossing for the 6-inch wafer scale. Two Ag nanomeshes, including pitch sizes of 7.5 and 10 μm, are used to obtain highly transparent (approximately 85% transmittance at a wavelength of 550 nm) and electrically conducting properties (below 10 Ω sq-1). The Ag nanomeshes are also distinguished according to the fabrication process, which is called transferred or embedded Ag nanomesh on polyethylene terephthalate (PET) substrate, in order to compare their stability against bending stress. Then the enhancement of bending stability when the Ag nanomesh is embedded in the PET substrate is confirmed.

  7. Silver nanoparticle-modified electrode for the determination of nitro compound-containing pesticides.

    PubMed

    de Lima, Camila Alves; Santana, Edson Roberto; Piovesan, Jamille Valéria; Spinelli, Almir

    2016-04-01

    This paper reports the electroanalytical determination of pendimethalin and ethyl parathion by square-wave adsorptive stripping voltammetry using a material comprised of chitosan-stabilized silver nanoparticles to modify a glassy carbon electrode. Under optimized experimental conditions, the peak current was found to vary linearly with the concentration of pendimethalin in the range of 70 to 2000 nmol L(-1) and with concentration of ethyl parathion in the range of 40 to 8000 nmol L(-1). Detection limits of 36 and 40 nmol L(-1) were obtained for pendimethalin and ethyl parathion, respectively. The silver - nanoparticle-modified electrode was successfully employed for the analysis of pesticides in tap and mineral water (pendimethalin) and in lettuce and honey (ethyl parathion) samples. Pendimethalin recovery was between 94 and 100 %, and ethyl parathion recovery was between 97 and 101 %, indicating no significant matrix interference effects on the analytical results. The accuracy of the electroanalytical methodology using the proposed modified electrode was also compared to that of the UV-vis spectrophotometric method. PMID:26873207

  8. Surface Modification of Silver Nanowires for Morphology and Processing Control in Composite Transparent Electrodes.

    PubMed

    Liang, Zhiming; Graham, Kenneth R

    2015-10-01

    Silver nanowires are attractive components for a number of materials and applications, including silver nanowire (AgNW)-polymer composites, electrically conductive coatings, and transparent electrodes. In this manuscript, the ability of thiols with hydrophobic to ionic end groups to bind to AgNW surfaces is investigated, followed by how the polarity of the surface modifying thiol influences the morphological and electrical properties of both AgNW/PEDOT:PSS blend films and pure AgNW networks. Utilizing surface modification of AgNWs with sodium 3-mercapto-1-propanesulfonate (MPS), morphologically homogeneous AgNW/PEDOT:PSS thin films with an order of magnitude lower sheet resistance at similar transmittance values than unmodified AgNWs are obtained with a one-step processing method. Brief optimization of MPS-AgNW/PEDOT:PSS blends yields a sheet resistance of 22.6 Ω/□ at 81.4% transmittance. PMID:26389535

  9. Tailored silver grid as transparent electrodes directly written by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan-Yuan; Zheng, Mei-Ling; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Ren, Xue-Liang; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2016-05-01

    We present the design and realization of silver grid transparent electrodes (SGTEs) easily fabricated by femtosecond laser direct writing of silver aqueous solution. The fabricated SGTEs with a sheet resistance down to 47 Ω/□ and optical transmittance up to 93% are demonstrated. These sheet resistance and transmittance values are comparable to commercially available indium tin oxide. High uniform morphology of the directly written SGTEs results in the ultra-stable tailored performance parameter at electronic and optical fields. The sheet resistance and transmittance can be tailored precisely by manipulating the filling fraction of the uniform SGTEs. This study provides an approach for creating SGTEs in a controllable fashion, and the SGTEs exhibit high transmittance and low sheet resistance, which could open up new avenues towards widespread application in electronics, photovoltaics, and optoelectronics.

  10. Capillary Printing of Highly Aligned Silver Nanowire Transparent Electrodes for High-Performance Optoelectronic Devices.

    PubMed

    Kang, Saewon; Kim, Taehyo; Cho, Seungse; Lee, Youngoh; Choe, Ayoung; Walker, Bright; Ko, Seo-Jin; Kim, Jin Young; Ko, Hyunhyub

    2015-12-01

    Percolation networks of silver nanowires (AgNWs) are commonly used as transparent conductive electrodes (TCEs) for a variety of optoelectronic applications, but there have been no attempts to precisely control the percolation networks of AgNWs that critically affect the performances of TCEs. Here, we introduce a capillary printing technique to precisely control the NW alignment and the percolation behavior of AgNW networks. Notably, partially aligned AgNW networks exhibit a greatly lower percolation threshold, which leads to the substantial improvement of optical transmittance (96.7%) at a similar sheet resistance (19.5 Ω sq(-1)) as compared to random AgNW networks (92.9%, 20 Ω sq(-1)). Polymer light-emitting diodes (PLEDs) using aligned AgNW electrodes show a 30% enhanced maximum luminance (33068 cd m(-2)) compared to that with random AgNWs and a high luminance efficiency (14.25 cd A(-1)), which is the highest value reported so far using indium-free transparent electrodes for fluorescent PLEDs. In addition, polymer solar cells (PSCs) using aligned AgNW electrodes exhibit a power conversion efficiency (PCE) of 8.57%, the highest value ever reported to date for PSCs using AgNW electrodes. PMID:26540011

  11. Fabrication of self-forming silver network as transparent conductive electrode with photoresist

    NASA Astrophysics Data System (ADS)

    Yang, Chaobin; Merlo, Juan M.; Burns, Michael J.; Kempa, Krzysztof; Naughton, Michael J.

    It has been reported that a metal wire network, obtained by sputtering with a self-cracking gel film mask, can function as a TCO replacement, perhaps reducing end device cost. Toward further process simplification and cost reduction, we are investigating various electroless deposition schemes to template a wire network electrode. We report here that a conventional photoresist film can be prepared with a network of microcracks and can be used as a mask to electrolessly deposit metal, e.g. silver. With this method, no vacuum chambers are required, and undeposited metal can even be recycled for additional depositions.

  12. All-solution processed semi-transparent perovskite solar cells with silver nanowires electrode

    NASA Astrophysics Data System (ADS)

    Yang, Kaiyu; Li, Fushan; Zhang, Jianhua; Perumal Veeramalai, Chandrasekar; Guo, Tailiang

    2016-03-01

    In this work, we report an all-solution route to produce semi-transparent high efficiency perovskite solar cells (PSCs). Instead of an energy-consuming vacuum process with metal deposition, the top electrode is simply deposited by spray-coating silver nanowires (AgNWs) under room temperature using fabrication conditions and solvents that do not damage or dissolve the underlying PSC. The as-fabricated semi-transparent perovskite solar cell shows a photovoltaic output with dual side illuminations due to the transparency of the AgNWs. With a back cover electrode, the open circuit voltage increases significantly from 1.01 to 1.16 V, yielding high power conversion efficiency from 7.98 to 10.64%.

  13. All-solution processed semi-transparent perovskite solar cells with silver nanowires electrode.

    PubMed

    Yang, Kaiyu; Li, Fushan; Zhang, Jianhua; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-03-01

    In this work, we report an all-solution route to produce semi-transparent high efficiency perovskite solar cells (PSCs). Instead of an energy-consuming vacuum process with metal deposition, the top electrode is simply deposited by spray-coating silver nanowires (AgNWs) under room temperature using fabrication conditions and solvents that do not damage or dissolve the underlying PSC. The as-fabricated semi-transparent perovskite solar cell shows a photovoltaic output with dual side illuminations due to the transparency of the AgNWs. With a back cover electrode, the open circuit voltage increases significantly from 1.01 to 1.16 V, yielding high power conversion efficiency from 7.98 to 10.64%. PMID:26821871

  14. Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

    PubMed

    Lee, Minoh; Ko, Yohan; Min, Byoung Koun; Jun, Yongseok

    2016-01-01

    Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production. PMID:26612081

  15. 3D Hollow Framework Silver Nanowire Electrodes for High-Performance Bottom-Contact Organic Transistors.

    PubMed

    Kim, Jiye; Lee, So Hee; Kim, Haekyoung; Kim, Se Hyun; Park, Chan Eon

    2015-07-01

    We successfully fabricated high performance bottom-contact organic field-effect transistors (OFETs) using silver nanowire (AgNW) network electrodes by spray deposition. The synthesized AgNWs have the dimensions of 40-80 nm in diameter and 30-80 μm in length and are randomly distributed and interconnected to form a 3D hollow framework. The AgNWs networks, deposited by spray coating, yield an average optical transmittance of up to 88% and a sheet resistance as low as 10 ohm/sq. For using AgNWs as source/drain electrodes of OFETs with a bottom-contact configuration, the large contact resistance at the AgNWs/organic channel remains a critical issue for charge injection. To enhance charge injection, we fabricate semiconductor crystals on the AgNW using an adsorbed residual poly(N-vinylpyrrolidone) layer. The resulting bottom-contact OFETs exhibit high mobility up to 1.02 cm(2)/(V s) and are similar to that of the top-contact Au electrodes OFETs with low contact resistance. A morphological study shows that the pentacene crystals coalesced to form continuous morphology on the nanowires and are highly interconnected with those on the channel. These features contribute to efficient charge injection and encourage the improvement of the bottom-contact device performance. Furthermore, the large contact area of individual AgNWs spreading out to the channel at the edge of the electrode also improves device performance. PMID:26083099

  16. From DVD to dendritic nanostructure silver electrode for hydrogen peroxide detection.

    PubMed

    Wen, Ying; Lin, Ai-Jing; Chen, Hui-Fen; Jiao, Ying-Zhi; Yang, Hai-Feng

    2013-03-15

    A facile method of multi-potential step-scan has been employed to fabricate the dendritic silver nanostructures on a silver thin film based digital video disc (DVD) electrode. The morphologies of the nanostructures, the chemical composition, and the crystal structure have been characterized by field-emission scanning electron microscopy, energy-dispersed x-ray spectroscopy, and x-ray diffraction, respectively. The electrocatalytic activity of the resulting electrode toward the electro-reduction of hydrogen peroxide (H(2)O(2)) has been examined via cyclic voltammetry and amperometric analysis. The excellent linear relationship between current response and H(2)O(2) concentration is observed in the range from 5.88×10(-7) to 6.73×10(-5) mol L(-1) and the detection limit is 2×10(-7) mol L(-1) (S/N=3). The as-developed method has been employed to determine H(2)O(2) concentration in real samples. PMID:23017675

  17. Silver nanowire/optical adhesive coatings as transparent electrodes for flexible electronics.

    PubMed

    Miller, Michael S; O'Kane, Jessica C; Niec, Adrian; Carmichael, R Stephen; Carmichael, Tricia Breen

    2013-10-23

    We present new flexible, transparent, and conductive coatings composed of an annealed silver nanowire network embedded in a polyurethane optical adhesive. These coatings can be applied to rigid glass substrates as well as to flexible polyethylene terephthalate (PET) plastic and elastomeric polydimethylsiloxane (PDMS) substrates to produce highly flexible transparent conductive electrodes. The coatings are as conductive and transparent as indium tin oxide (ITO) films on glass, but they remain conductive at high bending strains and are more durable to marring and scratching than ITO. Coatings on PDMS withstand up to 76% tensile strain and 250 bending cycles of 15% strain with a negligible increase in electrical resistance. Since the silver nanowire network is embedded at the surface of the optical adhesive, these coatings also provide a smooth surface (root mean squared surface roughness<10 nm), making them suitable as transparent conducting electrodes in flexible light-emitting electrochemical cells. These devices continue to emit light even while being bent to radii as low as 1.5 mm and perform as well as unstrained devices after 20 bending cycles of 25% tensile strain. PMID:24007382

  18. Optical properties and electrochemical dealloying of Gold-Silver alloy nanoparticles immobilized on composite thin-film electrodes

    NASA Astrophysics Data System (ADS)

    Starr, Christopher A.

    Gold-silver alloy nanoparticles (NPs) capped with adenosine 5'-triphosphate were synthesized by borohydride reduction of dilute aqueous metal precursors. High-resolution transmission electron microscopy showed the as-synthesized particles to be spherical with average diameters ~4 nm. Optical properties were measured by UV-Visible spectroscopy (UV-Vis), and the formation of alloy NPs was verified across all gold:silver ratios by a linear shift in the plasmon band maxima against alloy composition. The molar absorptivities of the NPs decreased non-linearly with increasing gold content from 2.0 x 108 M-1 cm-1 (lambdamax = 404 nm) for pure silver to 4.1 x 107 M-1 cm -1 (lambdamax = 511 nm) for pure gold. The NPs were immobilized onto transparent indium-tin oxide composite electrodes using layer-by-layer (LbL) deposition with poly(diallyldimethylammonium) acting as a cationic binder. The UV-Vis absorbance of the LbL film was used to calculate the surface coverage of alloy NPs on the electrode. Typical preparations had average NP surface coverages of 2.8 x 10-13 mol NPs/cm2 (~5% of cubic closest packing) with saturated films reaching ~20% of ccp for single-layer preparations (1.0 ~ 10-12 mol NPs/cm2). X-ray photoelectron spectroscopy confirmed the presence of alloy NPs in the LbL film and showed silver enrichment of the NP surfaces by ~9%. Irreversible oxidative dissolution (dealloying) of the less noble silver atoms from the NPs on LbL electrodes was performed by cyclic voltammetry (CV) in sulfuric acid. Alloy NPs with higher gold content required larger overpotentials for silver dealloying. Dealloying of the more-noble gold atoms from the alloy NPs was also achieved by CV in sodium chloride. The silver was oxidized first to cohesive silver chloride, and then gold dealloyed to soluble HAuCl 4- at higher potentials. Silver oxidation was inhibited during the first oxidative scan, but subsequent cycles showed typical, reversible silver-to-silver chloride voltammetry. The

  19. Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

    PubMed

    Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

    2013-05-31

    Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology. PMID:23619480

  20. Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics.

    PubMed

    Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

    2016-01-01

    We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37-0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics. PMID:26778621

  1. Silver nanowire based flexible electrodes with improved properties: High conductivity, transparency, adhesion and low haze

    SciTech Connect

    Kiran Kumar, A.B.V.; Wan Bae, Chang; Piao, Longhai Kim, Sang-Ho

    2013-08-01

    Graphical abstract: This graphical abstract illustrates the schematic representation of the main drawbacks and rectifications for AgNWs based transparent electrodes. - Highlights: • Films exhibited low sheet resistance and optical properties with R{sub s} ≤ 30 Ω/□ and T ≥ 90%. • We decreased haze to 2% by controlling AgNWs length, diameter, and concentration. • We achieved good adhesion for AgNWs on PET film. • There is no significant change in resistance in the bending angle from 0° to 180°, and on twisting. - Abstract: Recent work has been focusing on solution processable transparent electrodes for various applications including solar cells and displays. As well as, the research aims majorly at silver nanowires (AgNWs) to replace ITO. We enhance the transparent electrode performance as a function of optical and mechanical properties with low sheet resistance, by controlling the AgNWs accept ratios, ink composition, and processing conditions. The nanowire network of transparent films agrees with the 2D percolation law. The film transmittance values at 550 nm are coping with a reference ITO film. Sheet resistance and haze values are suitable for flexible electronic applications. We fabricate transparent flexible film using a low-cost processing technique.

  2. Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics

    NASA Astrophysics Data System (ADS)

    Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

    2016-01-01

    We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37-0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics.

  3. Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics

    PubMed Central

    Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

    2016-01-01

    We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37–0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics. PMID:26778621

  4. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhua; Li, Fushan; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-04-01

    In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH3NH3PbI3 perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm-2, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

  5. Pencil-trace on printed silver interdigitated electrodes for paper-based NO2 gas sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Jiankun; Huang, Lei; Lin, Youjie; Chen, Lu; Zeng, Ziyan; Shen, Leo; Chen, Qi; Shi, Wangzhou

    2015-04-01

    The pencil-drawn sensor is expected to enable a simple, low-cost, and reproducible paper-based sensor platform for widely deployed wireless environmental monitoring of NO2. Herein, we demonstrated a rapid prototyping of chemiresistor-type NO2 sensor by mechanical abrasion of an 8B pencil to form a stripe of uniform graphitic coating on printed silver interdigitated electrodes (IDEs). The Ag IDEs not only offer a low resistance but also provide the assembly of Ag nanoparticles into exfoliated graphene sheets for the paper-based NO2 gas sensors in order to realise much higher sensitivity and better reproducibility comparing with pencil-drawn sensors directly on weighing paper.

  6. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode

    NASA Astrophysics Data System (ADS)

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-01

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PEDOT:PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  7. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires.

    PubMed

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-21

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1). The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected. PMID:25588044

  8. Interface Roughening Dynamics of Spreading Droplets

    NASA Astrophysics Data System (ADS)

    Taitelbaum, Haim; Be'Er, Avraham; Hecht, Inbal; Frydman, Aviad; Lereah, Yossi

    2006-03-01

    We review our recent experimental data of interface roughening dynamics of spreading mercury droplets on thin films (silver or gold), obtained using optical microscopy and other techniques (AFM, SEM). We discuss the various results obtained for the roughness and growth exponents associated with the interface dynamics, and their universality classes. We analyze the temporal width fluctuations, obtained for single interfaces, and show that these fluctuations contain information on the lateral correlation length of these interfaces. We show how to extract this length from experimental data, and demonstrate the validity of this method in a wide range of growing interfaces (droplet spreading experiments as well as water imbibition on paper). References: 1. A. Be'er, Y. Lereah and H. Taitelbaum, Physica A, 285, 156 (2000). 2. A. Be'er, Y. Lereah, I. Hecht and H. Taitelbaum, Physica A, 302, 297 (2001). 3. A. Be'er, Y. Lereah, A. Frydman and H. Taitelbaum, Physica A, 314, 325 (2002). 4. A. Be'er and Y. Lereah, J. of Microscopy, 208, 148 (2002). 5. I. Hecht and H. Taitelbaum, Phys. Rev. E, 70, 046307 (2004). 6. A. Be'er, I. Hecht and H. Taitelbaum, Phys. Rev. E, 72, 031606 (2005). 7. I. Hecht, A. Be'er and H. Taitelbaum, Fluctuation and Noise Letters, 5, L319 (2005).

  9. Using silver nano-particle ink in electrode fabrication of high frequency copolymer ultrasonic transducers: modeling and experimental investigation.

    PubMed

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  10. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  11. Optimization of silver nanowire-based transparent electrodes: effects of density, size and thermal annealing.

    PubMed

    Lagrange, M; Langley, D P; Giusti, G; Jiménez, C; Bréchet, Y; Bellet, D

    2015-11-01

    Silver nanowire (AgNW) networks are efficient as flexible transparent electrodes, and are cheaper to fabricate than ITO (Indium Tin Oxide). Hence they are a serious competitor as an alternative to ITO in many applications such as solar cells, OLEDs, transparent heaters. Electrical and optical properties of AgNW networks deposited on glass are investigated in this study and an efficient method to optimize them is proposed. This paper relates network density, nanowire dimensions and thermal annealing directly to the physical properties of the nanowire networksusing original physical models. A fair agreement is found between experimental data and the proposed models. Moreover thermal stability of the nanowires is a key issue in thermal optimization of such networks and needs to be studied. In this work the impact of these four parameters on the networks physical properties are thoroughly investigated via in situ measurements and modelling, such a method being also applicable to other metallic nanowire networks. We demonstrate that this approach enables the optimization of both optical and electrical properties through modification of the junction resistance by thermal annealing, and a suitable choice of nanowire dimensions and network density. This work reports excellent optical and electrical properties of electrodes fabricated from AgNW networks with a transmittance T = 89.2% (at 550 nm) and a sheet resistance of Rs = 2.9 Ω □(-1), leading to the highest reported figure of merit. PMID:26437607

  12. Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Oh, Munsik; Jin, Won-Yong; Jun Jeong, Hyeon; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

    2015-09-01

    Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10-3 Ωcm2 was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters.

  13. Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes

    PubMed Central

    Oh, Munsik; Jin, Won-Yong; Jun Jeong, Hyeon; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

    2015-01-01

    Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10−3 Ωcm2 was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters. PMID:26333768

  14. Stability of silver nanowire based electrodes under environmental and electrical stresses.

    PubMed

    Mayousse, Céline; Celle, Caroline; Fraczkiewicz, Alexandra; Simonato, Jean-Pierre

    2015-02-01

    Flexible transparent electrodes fabricated with random networks of silver nanowires (AgNWs) have been widely studied in recent years. This approach appears to be a promising alternative to replace ITO (indium tin oxide) in many optoelectronic applications. Many successful integrations in functional devices have already evidenced the high potential of this technology, but unfortunately only very few studies have been dedicated so far to the stability of this material. We present here a study dealing with the alteration of the electrical properties of AgNW meshes when subjected to different stresses. We demonstrate that AgNW electrodes are very stable when stored under ambient atmosphere up to, at least, two and a half years. Accelerated ageing processes also reveal that concentrated H2S or exposure to light does not cause any significant sheet resistance modification. However, the combination of high relative humidity and high temperature seems to be more critical. In addition, long lasting contact (two years) with PEDOT:PSS can induce deterioration of the electrical properties. Similarly, AgNW/PEDOT:PSS hybrid materials exhibit weaker stability under electrical stress when compared to pristine AgNW networks. PMID:25559872

  15. Development of Silver-Free Silicon Photovoltaic Solar Cells with All-Aluminum Electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Cheng

    To date, the most popular and dominant material for commercial solar cells is crystalline silicon (or wafer-Si). It has the highest cell efficiency and cell lifetime out of all commercial solar cells. Although the potential of crystalline-Si solar cells in supplying energy demands is enormous, their future growth will likely be constrained by two major bottlenecks. The first is the high electricity input to produce crystalline-Si solar cells and modules, and the second is the limited supply of silver (Ag) reserves. These bottlenecks prevent crystalline-Si solar cells from reaching terawatt-scale deployment, which means the electricity produced by crystalline-Si solar cells would never fulfill a noticeable portion of our energy demands in the future. In order to solve the issue of Ag limitation for the front metal grid, aluminum (Al) electroplating has been developed as an alternative metallization technique in the fabrication of crystalline-Si solar cells. The plating is carried out in a near-room-temperature ionic liquid by means of galvanostatic electrolysis. It has been found that dense, adherent Al deposits with resistivity in the high 10--6 Ω-cm range can be reproducibly obtained directly on Si substrates and nickel seed layers. An all-Al Si solar cell, with an electroplated Al front electrode and a screen-printed Al back electrode, has been successfully demonstrated based on commercial p-type monocrystalline-Si solar cells, and its efficiency is approaching 15%. Further optimization of the cell fabrication process, in particular a suitable patterning technique for the front silicon nitride layer, is expected to increase the efficiency of the cell to ~18%. This shows the potential of Al electroplating in cell metallization is promising and replacing Ag with Al as the front finger electrode is feasible.

  16. High-Performance Silver Window Electrodes for Top-Illuminated Organic Photovoltaics Using an Organo-molybdenum Oxide Bronze Interlayer.

    PubMed

    Tyler, Martin S; Walker, Marc; Hatton, Ross A

    2016-05-18

    We report an organo-molybdenumn oxide bronze that enables the fabrication of high-performance silver window electrodes for top-illuminated solution processed organic photovoltaics without complicating the process of device fabrication. This hybrid material combines the function of wide-band-gap interlayer for efficient hole extraction with the role of metal electrode seed layer, enabling the fabrication of highly transparent, low-sheet-resistance silver window electrodes. Additionally it is also processed from ethanol, which ensures orthogonality with a large range of solution processed organic semiconductors. The key organic component is the low cost small molecule 3-mercaptopropionic acid, which (i) promotes metal film formation and imparts robustness at low metal thickness, (ii) reduces the contact resistance at the Ag/molybdenumn oxide bronze interface, (iii) and greatly improves the film forming properties. Silver electrodes with a thickness of 8 nm deposited by simple vacuum evaporation onto this hybrid interlayer have a sheet resistance as low as 9.7 Ohms per square and mean transparency ∼80% over the wavelength range 400-900 nm without the aid of an antireflecting layer, which makes them well-matched to the needs of organic photovoltaics and applicable to perovskite photovoltaics. The application of this hybrid material is demonstrated in two types of top-illuminated organic photovoltaic devices. PMID:27135377

  17. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-01

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa-1. The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present

  18. Preparation of novel mercury-doped silver nanoparticles film glassy carbon electrode and its application for electrochemical biosensor.

    PubMed

    Li, Mao-Guo; Shang, Yong-Jia; Gao, Ying-Chun; Wang, Guang-Feng; Fang, Bin

    2005-06-01

    A novel mercury-doped silver nanoparticles film glassy carbon (Ag/MFGC) electrode was prepared in this study. Electrochemical behaviors of cysteine on the Ag/MFGC electrode were investigated by electrochemical impedance spectroscopy and cyclic voltammetry (CV). The results indicated that cysteine could be strongly adsorbed on the surface of the Ag/MFGC electrode to form a thin layer. The doped electrode could catalyze the electrode reaction process of cysteine, and the cysteine displayed a pair of well-defined and nearly reversible CV peaks at the electrode in an acetate buffer solution (pH 5.0). The Ag/MFGC electrode was used for determination of cysteine by differential pulse voltammetry. The linear range was between 4.0x10(-7) and 1.3x10(-5) mol/L, with a detection limit of 1.0x10(-7) mol/L and a signal-to-noise ratio of 3. The relative standard deviation was 2.4% for seven successive determinations of 1.0x10(-5) mol/L cysteine. The determinations of cysteine in synthetic samples and urinal samples were carried out and satisfactory results were obtained. Amperometric application of the Ag/MFGC electrode as biosensors is proposed. PMID:15866527

  19. Role of silver current collector on the operational stability of selected cobalt-containing oxide electrodes for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Chen, Yubo; Wang, Fucun; Chen, Dengjie; Dong, Feifei; Park, Hee Jung; Kwak, Chan; Shao, Zongping

    2012-07-01

    The long-term stability for oxygen reduction reaction (ORR) of two typical perovskite cathode materials of SOFCs, i.e., Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and Sm0.5Sr0.5CoO3-δ (SSC), is investigated in a symmetric cell configuration under air condition at 700 °C using Sm0.2Ce0.8O1.9 (SDC) electrolyte substrate and silver current collectors. Moreover, two different methods of silver current collection are tested, i.e., whole electrode surface deposited with a diluted silver paste (CC-01) and a mesh-like current collector using concentrated silver paste (CC-02). Electrochemical impedance spectra are applied for stability investigations. With the CC-01 current collector, the performance of the electrode deteriorates significantly, although the initial performance is good. By contrast, fairly stable performance is obtained from symmetric cells with either BSCF or SSC + SDC electrodes using the CC-02 current collector, even though a phase transition is observed for BSCF. For instance, after approximately 800 h of continuous stability testing, the area-specific resistance of the BSCF electrode retains a value of approximately 0.065 Ω cm2, except for a slight fluctuation within the range of 0.06-0.07 Ω cm2. These findings reveal that both BSCF and SSC can be stably operated for ORR under symmetric cell conditions; however, an appropriate current collection method is crucial to achieving stable performance.

  20. Modified carbon-free silver electrodes for the use as cathodes in lithium-air batteries with an aqueous alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    Wittmaier, Dennis; Wagner, Norbert; Friedrich, K. Andreas; Amin, Hatem M. A.; Baltruschat, Helmut

    2014-11-01

    Gas diffusion electrodes with silver catalysts show a high activity towards oxygen reduction reaction in alkaline media but a rather poor activity towards oxygen evolution reaction. For the use in future lithium-air batteries with an aqueous alkaline electrolyte the activity of such electrodes must be improved significantly. As Co3O4 is a promising metal oxide catalyst for oxygen evolution in alkaline media, silver electrodes were modified with Co3O4. For comparison silver electrodes were also modified with IrO2. Due to the poor stability of carbon materials at high anodic potentials these gas diffusion electrodes were prepared without carbon support to improve especially the long-term stability. Gas diffusion electrodes were electrochemically investigated in an electrochemical half-cell arrangement. In addition to cyclic voltammograms electrochemical impedance spectroscopy (EIS) was carried out. SEM and XRD were used for the physical and morphological investigations. Investigations showed that silver electrodes containing 20 wt.% Co3O4 exhibited the highest performance and highest long-term stability. For comparison, rotating - ring - disc - electrode experiments have been performed using model electrodes with thin catalyst layers, showing that the amount of hydrogen peroxide evolved is negligible.

  1. High-performance flexible organic light-emitting diodes using embedded silver network transparent electrodes.

    PubMed

    Zhou, Lei; Xiang, Heng-Yang; Shen, Su; Li, Yan-Qing; Chen, Jing-De; Xie, Hao-Jun; Goldthorpe, Irene A; Chen, Lin-Sen; Lee, Shuit-Tong; Tang, Jian-Xin

    2014-12-23

    Because of their mechanical flexibility, organic light-emitting diodes (OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. The development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide (ITO) anodes. Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, flexible white OLEDs exhibit a power efficiency of 106 lm W(-1) at 1000 cd m(-2) with angular color stability, which is significantly higher than all other reports of flexible white OLEDs. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for use in a wide variety of high-performance flexible applications. PMID:25470615

  2. The role of chloride ions in rapid synthesis of ultra-long silver nanowires for flexible electrodes

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Tian, Yanhong; Ding, Su; Wang, Chunqing

    2016-07-01

    Ultra-long silver nanowires (AgNWs) could be an ideal material to replace the commercial used indium tin oxide in highly conductive and transparent electrodes field. In this report, AgNWs with mean length of 102 μm and even 268 μm have been synthesized through a rapid and one-step polyol method within only 40 min. The effective synthesis was contributed to the relatively high concentration of Cl‑ which facilitated the generation of silver five-twined seeds by heterogeneous nucleation during the nucleation process. By varying the ratio of Cl‑, AgNWs with various diameters ranging from 60 to 141 nm could be obtained. Moreover, AgNWs based electrodes were prepared on paper and polyethylene terephthalate (PET) substrates and the sheet resistance of the PET based transparent electrode were measured to be 14 Ω sq‑1 at optical transmittance of 87%. The mechanical properties of the ultra-long AgNWs based electrodes were also characterized.

  3. Strain sensitivity and durability in p-type and n-type organic thin-film transistors with printed silver electrodes

    PubMed Central

    Fukuda, Kenjiro; Hikichi, Kenta; Sekine, Tomohito; Takeda, Yasunori; Minamiki, Tsukuru; Kumaki, Daisuke; Tokito, Shizuo

    2013-01-01

    Mechanical flexibility and compatibility of printing processes are key advantage that organic electronic devices have over conventional inorganic devices. However, one of the major remaining issues for organic devices is insufficient mechanical durability of printed electrodes. Here we have investigated the mechanical durability of both p-type and n-type organic thin-film transistors (TFTs) with ink-jet printed silver electrodes from silver nanoparticle inks. The modified silver nanoparticle inks enabled the strong adhesion to the underlying polymer layer, and the fabricated organic TFTs exhibited excellent reproducibility in the bending cycle tests. The strong channel length dependence on the strain sensitivity was observed in both p-type and n-type organic TFTs. The organic TFTs with a short-channel exhibited higher sensitivity to the bending strain. These results suggest that the flexible organic TFTs with printed silver electrodes have excellent mechanical durability and are useful for bending and strain sensors. PMID:23788235

  4. Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on reduced graphene oxide and silver nanoparticles nanocomposite modified electrode.

    PubMed

    Palanisamy, Selvakumar; Karuppiah, Chelladurai; Chen, Shen-Ming

    2014-02-01

    The direct electrochemistry of glucose oxidase (GOx) was successfully realized on electrochemically reduced graphene oxide and silver nanoparticles (RGO/Ag) nanocomposite modified electrode. The fabricated nanocomposite was characterized by field emission scanning electron microscope and energy dispersive spectroscopy. The GOx immobilized nanocomposite modified electrode showed a pair of well-defined redox peaks with a formal potential (E°) of -0.422 V, indicating that the bioactivity of GOx was retained. The heterogeneous electron transfer rate constant (Ks) of GOx at the nanocomposite was calculated to be 5.27 s(-1), revealing a fast direct electron transfer of GOx. The GOx immobilized RGO/Ag nanocomposite electrode exhibited a good electrocatalytic activity toward glucose over a linear concentration range from 0.5 to 12.5 mM with a detection limit of 0.16 mM. Besides, the fabricated biosensor showed an acceptable sensitivity and selectivity for glucose. PMID:24184536

  5. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

  6. Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

    PubMed

    Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

    2015-08-19

    A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test. PMID:26200807

  7. Synthesis of silver nanowires using hydrothermal technique for flexible transparent electrode application

    NASA Astrophysics Data System (ADS)

    Vijila, C. V. Mary; Rahman, K. K. Arsina; Parvathy, N. S.; Jayaraj, M. K.

    2016-05-01

    Transparent conducting films are becoming increasingly interesting because of their applications in electronics industry such as their use in solar energy applications. In this work silver nanowires were synthesized using solvothermal method by reducing silver nitrate and adding sodium chloride for assembling silver into nanowires. Absorption spectra of nanowires in the form of a dispersion in deionized water, AFM and SEM images confirm the nanowire formation. Solution of nanowire was coated over PET films to obtain transparent conducting films.

  8. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  9. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    NASA Astrophysics Data System (ADS)

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-07-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

  10. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes.

    PubMed

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-01-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

  11. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    PubMed Central

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-01-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

  12. Decolorization of C. I. Reactive Orange 4 and Textile Effluents by Electrochemical Oxidation Technique using Silver-Carbon Composite Electrode.

    PubMed

    Nordin, Norazzizi; Fathrita Mohd Amir, Siti; Rahimi Yusop, Muhammad; Rozali Othman, Mohamed

    2015-01-01

    In this study, the electrochemical oxidation of C. I. Reactive Orange 4 (RO4) on a silver-carbon composite (AgC-PVC) electrode was studied using the cyclic voltammetry, potential liner V, and electrolysis methods. The AgC-PVC electrode was used as the working electrode in the electrochemical measurement of RO4 in the presence of NaCl as a supporting electrolyte. The UV-Vis spectra of RO4 after the electrochemical oxidation showed the complete decolorization of the solution. The electrolysis products were characterized using FTIR and GC-MS. The results showed that in the presence of OCl- as an active oxidant, RO4 molecules are broken down into several lower-molecular-weight molecules by the electrochemical technique. The electrode used was also able to reduce the COD, BOD(5) and surfactant contents in the textile effluents using a pilot scale reactor. This proved that the prepared AgC-PVC electrode was beneficial for removing both the color and other pollutants from textile effluents. PMID:26454599

  13. Mussel-Inspired Polydopamine-Functionalized Graphene as a Conductive Adhesion Promoter and Protective Layer for Silver Nanowire Transparent Electrodes.

    PubMed

    Miao, Jinlei; Liu, Haihui; Li, Wei; Zhang, Xingxiang

    2016-05-31

    For the scalable fabrication of transparent electrodes and optoelectronic devices, excellent adhesion between the conductive films and the substrates is essential. In this work, a novel mussel-inspired polydopamine-functionalized graphene/silver nanowire hybrid nanomaterial for transparent electrodes was fabricated in a facile manner. Graphene oxide (GO) was functionalized and reduced by polydopamine while remaining stable in water without precipitation. It is shown that the polydopamine-functionalized GO (PFGO) film adhered to the substrate much more easily and more uniformly than the GO film. The PFGO film had a sheet resistance of ∼3.46 × 10(8) Ω/sq and a transparency of 78.2%, with excellent thermal and chemical stability; these characteristics are appropriate for antistatic coatings. Further reduced PFGO (RPFGO) as a conductive adhesion promoter and protective layer for the Ag nanowire (AgNW) significantly enhanced the adhesion force between AgNW networks and the substrate. The RPFGO-AgNW electrode was found to have a sheet resistance of 63 Ω/sq and a transparency of 70.5%. Moreover, the long-term stability of the RPFGO-AgNW electrode was greatly enhanced via the effective protection of the AgNW by RPFGO. These solution-processed antistatic coatings and electrodes have tremendous potential in the applications of optoelectronic devices as a result of their low production cost and facile processing. PMID:27142815

  14. Synthesis and characterization of conductive silver ink for electrode printing on cellulose film

    NASA Astrophysics Data System (ADS)

    Khondoker, Mohammad Abu Hasan; Mun, Seong Cheol; Kim, Jaehwan

    2013-08-01

    Silver nanoparticles with size less than 50 nm were synthesized from silver nitrate, polyvinylpyrrolidone (PVP) and ethylene glycol, where these chemicals acted as metal precursor, stabilizer and reducing agent, respectively. Then a conductive silver ink was prepared with a suitable solvent by adding a viscosifier, hydroxyethyl-cellulose (HEC), and a surfactant, diethylene glycol (DEG). The combined effect of both viscosifier and surfactant on the physical property of the silver ink was analyzed by measuring the contact angle of the silver ink on a cellulose film. Moreover, the influences of PVP molecular weight and reaction temperature on the size of the silver nanoparticles were analyzed. Then the silver ink was coated on the cellulose film by spin coating and the effects of different solvents, sintering temperatures and solid contents on its electrical resistivity were examined. It was found that, with 50 % co-solvent of deionized water and DEG and solid content of around 50 %, the silver ink exhibited the lowest resistivity. This ink can be used for inkjet printing of conductive patterns on cellulose films.

  15. A Raman spectroscopic and electrochemical study of the photoinduced crystallization of triethylenediamine triiodide upon a silver electrode

    NASA Astrophysics Data System (ADS)

    Ozek, Toru; Irish, Donald E.

    1991-02-01

    When a silver electrode, electrochemically coated with AgI, is immersed in an electrolyte containing NaI and the diprotonated form of 1,4-diazabicyclo 2.2.2 octane (abbreviated DABCO-H22+), and is bathed in 514.5 nm radiation from an argon ion laser through the objective of the microscope attachment of the DILOR Omars-89 Raman spectrophotometer, crystals form from the focal point. These are attributed to DABCO-h22+ 213-. Both spectroscopic and electrochemical experiments are described and interrelated. A mechanism for this photoinduced electrochemical crystal growth is presented.

  16. Voltammetric analysis of ordnance materials. Part 2: A portable digital voltammeter for use with a silver wire working electrode

    NASA Astrophysics Data System (ADS)

    Fine, D. A.; Reeve, D. A.; Dickus, R. A.

    1984-12-01

    An inexpensive, portable, digital voltammeter has been designed and built at NWC. The instrument is intended for use with a silver wire working electrode. The voltammeter was built in response to a need on the part of Navy facilities for the monitoring of effluent water from the carbon column cleanup process used to remove propyleneglycoldinitrate from Otto fuel waste water. The instrument may also be used for the monitoring of contaminants such as nitroglycerin, dinitrotoluene, trinitrotoluene and nitroguanidine. This report describes in detail the construction, circuitry, software and operational features of the instrument.

  17. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide

    NASA Astrophysics Data System (ADS)

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Phan, Vu Ngoc; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-01

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20–40 Ω/□ to 7–15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%.

  18. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide.

    PubMed

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Ngoc Phan, Vu; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-19

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20-40 Ω/□ to 7-15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%. PMID:27378668

  19. Dynamic silver speciation as studied with fluorous-phase ion-selective electrodes: Effect of natural organic matter on the toxicity and speciation of silver.

    PubMed

    Mousavi, Maral P S; Gunsolus, Ian L; Pérez De Jesús, Carlos E; Lancaster, Mitchell; Hussein, Kadir; Haynes, Christy L; Bühlmann, Philippe

    2015-12-15

    The widespread application of silver in consumer products and the resulting contamination of natural environments with silver raise questions about the toxicity of Ag(+) in the ecosystem. Natural organic matter, NOM, which is abundant in water supplies, soil, and sediments, can form stable complexes with Ag(+), altering its bioavailability and toxicity. Herein, the extent and kinetics of Ag(+) binding to NOM, matrix effects on Ag(+) binding to NOM, and the effect of NOM on Ag(+) toxicity to Shewanella oneidensis MR-1 (assessed by the BacLight viability assay) were quantitatively studied with fluorous-phase Ag(+) ion-selective electrodes (ISEs). Our findings show fast kinetics of Ag(+) and NOM binding, weak Ag(+) binding for Suwannee River humic acid, fulvic acid, and aquatic NOM, and stronger Ag(+) binding for Pony Lake fulvic acid and Pahokee Peat humic acid. We quantified the effects of matrix components and pH on Ag(+) binding to NOM, showing that the extent of binding greatly depends on the environmental conditions. The effect of NOM on the toxicity of Ag(+) does not correlate with the extent of Ag(+) binding to NOM, and other forms of silver, such as Ag(+) reduced by NOM, are critical for understanding the effect of NOM on Ag(+) toxicity. This work also shows that fluorous-phase Ag(+) ISEs are effective tools for studying Ag(+) binding to NOM because they can be used in a time-resolved manner to monitor the activity of Ag(+) in situ with high selectivity and without the need for extensive sample preparation. PMID:26284896

  20. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  1. High performance supercapacitor based on graphene-silver nanoparticles-polypyrrole nanocomposite coated on glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Kalambate, Pramod K.; Dar, Riyaz A.; Karna, Shashi P.; Srivastava, Ashwini K.

    2015-02-01

    In the current study, we present a new hybrid material of double layer capacitive material graphene (GNS), pseudo capacitive polypyrrole (PPY) and highly conducting silver nanoparticles (AgNPs). Graphene/Silver nanoparticles/polypyrrole (GNS/AgNPs/PPY) composite has been synthesized by in situ oxidative polymerization of pyrrole in the presence of GNS and AgNPs. The different mass concentrations of AgNPs were utilized to improve the capacitive performance of supercapacitor. Characterization of the electrode material has been carried out by X-ray diffraction, Raman spectroscopy, Thermal methods, Scanning electron microscopy (SEM) and Transmission electron microscopy. SEM images showed that PPY nanoparticles uniformly coated on graphene sheets along with AgNPs. Electrochemical characterization of the electrode surface has been carried out by means of cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. Remarkably, GNS/AgNPs/PPY exhibits specific capacitance of 450 F g-1 at current density of 0.9 mA g-1, which is far better than GNS/PPY (288 F g-1), AgNPs/PPY (216 F g-1) and PPY (153 F g-1). Furthermore, GNS/AgNPs/PPY shows high charge-discharge reversibility and retaining over 92.0% of its initial value after 1000 cycles. The cyclic stability of the composite is improved due to the synergistic effect of GNS, AgNPs and PPY.

  2. From surface roughening to QCD string theory

    SciTech Connect

    Keisuke Jimmy Juge et al.

    2001-05-23

    Surface critical phenomena and the related onset of Goldstone modes represent fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement and string formation are presented. Problems with a simple string description of the large Wilson surface are discussed.

  3. Non-enzymatic amperometric detection of hydrogen peroxide in human blood serum samples using a modified silver nanowire electrode.

    PubMed

    Thirumalraj, Balamurugan; Zhao, Duo-Han; Chen, Shen-Ming; Palanisamy, Selvakumar

    2016-05-15

    In this paper, we report a highly sensitive amperometric H2O2 sensor based on silver nanowires (AgNWs) modified screen printed carbon electrode. The AgNWs were synthesized using polyol method. The synthesized AgNWs were characterized by scanning electron microscopy, UV-vis spectroscopy and X-ray diffraction techniques. The average diameter and length of the synthesized AgNWs were found as 86±5 and 385nm, respectively. Under optimum conditions, the AgNWs modified electrode shows a stable amperometric response for H2O2 and was linear over the concentrations ranging from 0.3 to 704.8μM. The non-enzymatic sensor showed a high sensitivity of 662.6μAmM(-1)cm(-2) with a detection limit of 29nM. The response time of the sensor was found as 2s. Furthermore, the AgNWs modified electrode exhibited a good recovery of H2O2 (94.3%) in the human blood serum samples. PMID:26939075

  4. Nanoscale current spreading analysis in solution-processed graphene oxide/silver nanowire transparent electrodes via conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Shaw, Joseph E.; Perumal, Ajay; Bradley, Donal D. C.; Stavrinou, Paul N.; Anthopoulos, Thomas D.

    2016-05-01

    We use conductive atomic force microscopy (CAFM) to study the origin of long-range conductivity in model transparent conductive electrodes composed of networks of reduced graphene oxide (rGOX) and silver nanowires (AgNWs), with nanoscale spatial resolution. Pristine networks of rGOX (1-3 monolayers-thick) and AgNWs exhibit sheet resistances of ˜100-1000 kΩ/□ and 100-900 Ω/□, respectively. When the materials are deposited sequentially to form bilayer rGOX/AgNW electrodes and thermally annealed at 200 °C, the sheet resistance reduces by up to 36% as compared to pristine AgNW networks. CAFM was used to analyze the current spreading in both systems in order to identify the nanoscale phenomena responsible for this effect. For rGOX networks, the low intra-flake conductivity and the inter-flake contact resistance is found to dominate the macroscopic sheet resistance, while for AgNW networks the latter is determined by the density of the inter-AgNW junctions and their associated resistance. In the case of the bilayer rGOX/AgNWs' networks, rGOX flakes are found to form conductive "bridges" between AgNWs. We show that these additional nanoscopic electrical connections are responsible for the enhanced macroscopic conductivity of the bilayer rGOX/AgNW electrodes. Finally, the critical role of thermal annealing on the formation of these nanoscopic connections is discussed.

  5. The optimization of Ag/Ag2S electrode using carrier electroplating of nano silver particles and its preliminary application to offshore Kueishan Tao, Taiwan

    NASA Astrophysics Data System (ADS)

    Ding, Qian; Pan, Yi-wen; Huang, Yuan-feng; Chen, Chen-Tung Arthur; Ye, Ying

    2015-12-01

    Eutrophication-induced ocean acidification is causing a dramatic ecologic change in the coastal ocean. A more acidic ocean would lead to more volatile H2S in the coastal ocean, especially in the area where shallow hydrothermal vents exist. Therefore, the early detection of H2S and its associates is needed. In this study, the preparation method for and the detection limit of an Ag/Ag2S electrode were optimized by coating the electrode with micro-scale to nano-scale silver particles. The size of the silver particles was dependent on the electroplating power used to produce them: (1) direct current power made micrometer scale silver particles, and (2) direct current carrier power made nano-scale silver particles. As a result, the detection limits of [S2-] of the Ag/Ag2S electrode made using direct current and direct carrier current were improved to 1×10-5 mol L-1 and 1×10-7 mol L-1, respectively. Such improvements were mostly due to the fact that nano silver particles have larger surface area and higher surface energy. The Ag/Ag2S electrode made by direct carrier current method was then mounted to a multi-parameter sensor (including a pH and an Eh electrode) used to search of new hydrothermal vents near the Kueishan Tao in May, 2011. A new hydrothermal vent was discovered based on pH, Eh and H2S anomalies at three depths. A clear [S2-] signal anomaly was observed from the top sensor indicating the dispersive pattern of the hot fluid near this shallow vent site. This could also provide additional information on the dispersion pattern of anthropogenic pollutants in the coastal ocean.

  6. Flexible electrochromic supercapacitor hybrid electrodes based on tungsten oxide films and silver nanowires.

    PubMed

    Shen, Liuxue; Du, Lianhuan; Tan, Shaozao; Zang, Zhigang; Zhao, Chuanxi; Mai, Wenjie

    2016-05-01

    We successfully fabricate flexible electrochromic supercapacitor (SC) electrodes employing novel flexible transparent conducting substrates. The as-synthesized flexible electrochromic SC electrodes exhibit great electrochemical performances (13.6 mF cm(-2), 138.2 F g(-1)) and high coloration efficiency (80.2 cm(2) C(-1)), which demonstrate their potential applications in flexible smart windows combining energy storage and electrochromism. PMID:27087032

  7. Ultrasmooth silver thin film electrodes with high polar liquid wettability for OLED microcavity application.

    PubMed

    Cioarec, Cristina; Melpignano, Patrizia; Gherardi, Nicolas; Clergereaux, Richard; Villeneuve, Christina

    2011-04-01

    For a lab-on-chip application, we fabricate a blue bottom emitting strong microcavity organic light emitting diode (OLED), using very smooth and optically thin (25 nm) silver film as anode on a glass substrate. To improve the hole injection in the OLED device, PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)) has been used, so the silver anode must present not only a very smooth surface but also a strong adherence on the glass and a high wettability to allow a good PEDOT-PSS spin coating deposition. To obtain these physical properties, different 5 nm thick nucleation layers (germanium, chromium, and hydrogenated amorphous carbon) have been used to grow the silver thin films by e-beam deposition. The Ge/Ag bilayer presents all the desired properties: this bilayer, investigated by ellipsometry, optical profilometry, contact angle measurements, and XPS analysis, highlights an ultrasmooth surface correlated with the film growth mode and a high wettability related to its surface chemical composition. PMID:21391637

  8. Effects of surface roughening of Nafion 117 on the mechanical and physicochemical properties of ionic polymer–metal composite (IPMC) actuators

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Zhu, Zicai; Liu, Jiayu; Chang, Longfei; Chen, Hualing

    2016-08-01

    In this paper, the surface of a Nafion membrane was roughened by the sandblasting method, mainly considering the change of sandblasting time and powder size. The roughened surfaces were characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. The key surface parameters, such as Sa (the arithmetical mean deviation of the specified surface profile), SSA (the surface area ratio before and after roughening) and the area measurement on the histogram from the CLSM images, were extracted and evaluated from the roughened membranes. Also, the detailed change in surface and interfacial electrodes were measured and discussed together with the surface resistance, equivalent modulus, capacitance and performances of IPMC actuators based on the roughened membranes. The results show that a suitable sandblasting condition, resulting in the decrease in the bending stiffness and the increase in the interface area closely related to the capacitance, can effectively increase the electromechanical responses of IPMCs. Although the surface roughening by sandblasting caused a considerable lowering of mechanical strength, it was very effective for enlarging the interfacial area between Nafion membrane and the electrode layers, and for forming a penetrated electrode structure, which facilitated improvement of the surface resistance and capacitance characteristics of IPMCs. In this work, a quantitative relationship was built between the topography of Nafion membrane surface and electromechanical performance of IPMCs by means of sandblasting.

  9. Annealing-free, flexible silver nanowire-polymer composite electrodes via a continuous two-step spray-coating method.

    PubMed

    Choi, Dong Yun; Kang, Hyun Wook; Sung, Hyung Jin; Kim, Sang Soo

    2013-02-01

    For the realization of high-efficiency flexible optoelectronic devices, transparent electrodes should be fabricated through a low-temperature process and have the crucial feature of low surface roughness. In this paper, we demonstrated a two-step spray-coating method for producing large-scale, smooth and flexible silver nanowire (AgNW)-poly3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) composite electrodes. Without the high-temperature annealing process, the conductivity of the composite film was improved via the lamination of highly conductive PEDOT:PSS modified by dimethyl sulfoxide (DMSO). Under the room temperature process condition, we fabricated the AgNW-PEDOT:PSS composite film showing an 84.3% mean optical transmittance with a 10.76 Ω sq(-1) sheet resistance. The figure of merit Φ(TC) was higher than that obtained from the indium tin oxide (ITO) films. The sheet resistance of the composite film slightly increased less than 5.3% during 200 cycles of tensile and compression folding, displaying good electromechanical flexibility for use in flexible optoelectronic applications. PMID:23241687

  10. Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction.

    PubMed

    Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

    2015-01-01

    The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm(-1) (at 0 % strain) and 322.8 S cm(-1) (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles. PMID:26383845

  11. Efficient Nickel Sulfide and Graphene Counter Electrodes Decorated with Silver Nanoparticles and Application in Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Yue, Gentian; Li, Fumin; Yang, Guang; Zhang, Weifeng

    2016-05-01

    We reported a facile two-step electrochemical-chemical approach for in situ growth of nickel sulfide and graphene counter electrode (CE) decorated with silver nanoparticles (signed NiS/Gr-Ag) and served in dye-sensitized solar cells (DSSCs). Under optimum conditions, the DSSC achieved a remarkable power conversion efficiency of 8.36 % assembled with the NiS/Gr-Ag CE, much higher than that based on the Pt CE (7.76 %). The surface morphology of NiS/Gr-Ag CE exhibited a smooth surface with cross-growth of NiS, graphene, and Ag nanoparticles, which was beneficial to the fast mass transport of electrolytes; increased the contact area of electrolytes and active materials; and enabled to speed up the reduction of triiodide to iodide. The research on the electrochemical properties also showed that the NiS/Gr-Ag CE possessed lower charge transfer resistance and more excellent electrocatalytic activity in iodide/triiodide electrolyte compared to the Pt electrode.

  12. Efficient Nickel Sulfide and Graphene Counter Electrodes Decorated with Silver Nanoparticles and Application in Dye-Sensitized Solar Cells.

    PubMed

    Yue, Gentian; Li, Fumin; Yang, Guang; Zhang, Weifeng

    2016-12-01

    We reported a facile two-step electrochemical-chemical approach for in situ growth of nickel sulfide and graphene counter electrode (CE) decorated with silver nanoparticles (signed NiS/Gr-Ag) and served in dye-sensitized solar cells (DSSCs). Under optimum conditions, the DSSC achieved a remarkable power conversion efficiency of 8.36 % assembled with the NiS/Gr-Ag CE, much higher than that based on the Pt CE (7.76 %). The surface morphology of NiS/Gr-Ag CE exhibited a smooth surface with cross-growth of NiS, graphene, and Ag nanoparticles, which was beneficial to the fast mass transport of electrolytes; increased the contact area of electrolytes and active materials; and enabled to speed up the reduction of triiodide to iodide. The research on the electrochemical properties also showed that the NiS/Gr-Ag CE possessed lower charge transfer resistance and more excellent electrocatalytic activity in iodide/triiodide electrolyte compared to the Pt electrode. PMID:27142877

  13. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

    PubMed

    Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. PMID:27612735

  14. Optimization of method for zinc analysis in several bee products on renewable mercury film silver based electrode.

    PubMed

    Opoka, Włodzimierz; Szlósarczyk, Marek; Maślanka, Anna; Piech, Robert; Baś, Bogusław; Włodarczyk, Edyta; Krzek, Jan

    2013-01-01

    Zinc is an interesting target for detection as it is one of the elements necessary for the proper functioning of the human body, its excess and deficiency can cause several symptoms. Several techniques including electrochemistry have been developed but require laboratory equipment, preparative steps and mercury or complex working electrodes. We here described the development of a robust, simple and commercially available electrochemical system. Differential pulse (DP) voltammetry was used for this purpose with the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) and 0.05 M KNO3 solution as a supporting electrolyte. The effect of various factors such as: preconcentration potential and time, pulse amplitude and width, step potential and supporting electrolyte composition are optimized. The limits of detection (LOD) and quantification (LOQ) were 1.62 ng/mL and 4.85 ng/mL, respectively. The repeatability of the method at a concentration level of the analyte as low as 3 ng/mL, expressed as RSD is 3.5% (n = 6). Recovery was determined using certified reference material: Virginia Tobacco Leaves (CTA-VTL-2). The recovery of zinc ranged from 96.6 to 106.5%. The proposed method was successfully applied for determination of zinc in bee products (honey, propolis and diet supplements) after digestion procedure. PMID:24383319

  15. Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

    PubMed Central

    Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

    2015-01-01

    The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles. PMID:26383845

  16. Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, Jihun; Yang, Junghee; Lee, Hyoyoung

    2015-09-01

    The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles.

  17. Spatial Competition: Roughening of an Experimental Interface

    PubMed Central

    Allstadt, Andrew J.; Newman, Jonathan A.; Walter, Jonathan A.; Korniss, G.; Caraco, Thomas

    2016-01-01

    Limited dispersal distance generates spatial aggregation. Intraspecific interactions are then concentrated within clusters, and between-species interactions occur near cluster boundaries. Spread of a locally dispersing invader can become motion of an interface between the invading and resident species, and spatial competition will produce variation in the extent of invasive advance along the interface. Kinetic roughening theory offers a framework for quantifying the development of these fluctuations, which may structure the interface as a self-affine fractal, and so induce a series of temporal and spatial scaling relationships. For most clonal plants, advance should become spatially correlated along the interface, and width of the interface (where invader and resident compete directly) should increase as a power function of time. Once roughening equilibrates, interface width and the relative location of the most advanced invader should each scale with interface length. We tested these predictions by letting white clover (Trifolium repens) invade ryegrass (Lolium perenne). The spatial correlation of clover growth developed as anticipated by kinetic roughening theory, and both interface width and the most advanced invader’s lead scaled with front length. However, the scaling exponents differed from those predicted by recent simulation studies, likely due to clover’s growth morphology. PMID:27465518

  18. Spatial Competition: Roughening of an Experimental Interface.

    PubMed

    Allstadt, Andrew J; Newman, Jonathan A; Walter, Jonathan A; Korniss, G; Caraco, Thomas

    2016-01-01

    Limited dispersal distance generates spatial aggregation. Intraspecific interactions are then concentrated within clusters, and between-species interactions occur near cluster boundaries. Spread of a locally dispersing invader can become motion of an interface between the invading and resident species, and spatial competition will produce variation in the extent of invasive advance along the interface. Kinetic roughening theory offers a framework for quantifying the development of these fluctuations, which may structure the interface as a self-affine fractal, and so induce a series of temporal and spatial scaling relationships. For most clonal plants, advance should become spatially correlated along the interface, and width of the interface (where invader and resident compete directly) should increase as a power function of time. Once roughening equilibrates, interface width and the relative location of the most advanced invader should each scale with interface length. We tested these predictions by letting white clover (Trifolium repens) invade ryegrass (Lolium perenne). The spatial correlation of clover growth developed as anticipated by kinetic roughening theory, and both interface width and the most advanced invader's lead scaled with front length. However, the scaling exponents differed from those predicted by recent simulation studies, likely due to clover's growth morphology. PMID:27465518

  19. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  20. Patterning Method for Silver Nanoparticle Electrodes in Fully Solution-Processed Organic Thin-Film Transistors Using Selectively Treated Hydrophilic and Hydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Fukuda, Kenjiro; Takeda, Yasunori; Kobayashi, Yu; Shimizu, Masahiro; Sekine, Tomohito; Kumaki, Daisuke; Kurihara, Masato; Sakamoto, Masatomi; Tokito, Shizuo

    2013-05-01

    Fully solution-processed organic thin-film transistor (OTFT) devices have been fabricated with simple patterning process at a relatively low process temperature of 100 °C. In the patterning process, a hydrophobic amorphous fluoropolymer material, which was used as the gate dielectric layer and the underlying base layer, was treated with an oxygen plasma to selectively change its surface wetting properties from hydrophobic to hydrophilic. Silver source and drain electrodes were successfully formed in the treated areas with highly uniform line widths and without residues between the electrodes. Nonuniformities in the thickness of the silver electrodes originating from the “coffee-ring” effect were suppressed by optimizing the blend of solvents used with the silver nanoparticles, such that the printed electrodes are appropriate for bottom-gate OTFT devices. A fully solution-processed OTFT device using a polymer semiconductor material (PB16TTT) exhibited good electrical performance with no hysteresis in its transfer characteristics and with good linearity in its output characteristics. A relatively high carrier mobility of 0.14 cm2 V-1 s-1 and an on/off ratio of 1×105 were obtained with the fabricated TFT device.

  1. Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes.

    PubMed

    Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

    2016-01-01

    In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process. PMID:27553755

  2. Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes

    PubMed Central

    Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

    2016-01-01

    In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process. PMID:27553755

  3. Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells with Good Mechanical Stability.

    PubMed

    Kim, Wanjung; Kim, Soyeon; Kang, Iljoong; Jung, Myung Sun; Kim, Sung June; Kim, Jung Kyu; Cho, Sung Min; Kim, Jung-Hyun; Park, Jong Hyeok

    2016-05-10

    Herein, we report a tailored Ag mesh electrode coated with poly(3,4-ethylenedioxythiophene) (PEDOT) polymer on a flexible polyethylene terephthalate (PET) substrate. The introduction of this highly conductive polymer solves the existing problems of Ag mesh-type transparent conductive electrodes, such as high pitch, roughness, current inhomogeneity, and adhesion problems between the Ag mesh grid and PEDOT polymer or PET substrate, to result in excellent electron spreading from the discrete Ag mesh onto the entire surface without sacrificing sheet conductivity and optical transparency. Based on this hybrid anode, we demonstrate highly efficient flexible polymer solar cells (PSCs) with a high fill factor of 67.11 %, which results in a power conversion efficiency (PCE) of 6.9 % based on a poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl}):[6,6]-phenyl-C71 -butyric acid methyl ester bulk heterojunction device. Furthermore, the PSC device with the Ag mesh electrode also exhibits a good mechanical bending stability, as indicated by a 70 % retention of the initial PCE after 500 bending cycles compared with the PSC device with a PET/indium tin oxide electrode, which retained 0 % of the initial PCE after 300 bending cycles. PMID:27038288

  4. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

    PubMed

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-28

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process. PMID:26465213

  5. Redox Equilibria of Cytochrome C3 Immobilised on Self-Assembled Monolayers Coated Silver Electrodes

    NASA Astrophysics Data System (ADS)

    Di Paolo, R. E.; Rivas, L.; Murgida, D.; Hildebrandt, P.

    2005-01-01

    Cytochromes c3 are soluble electron transfer proteins in the periplasm of sulphate-reducing bacteria. They act as electron-proton couplers between hydrogenase and the electron transfer chain of sulphate respiration. In this work, cytochrome c3 (Cyt-c3) obtained from both Desulfovibrio vulgaris and Desulfovibrio gigas, is electrostatically adsorbed on Ag electrodes coated with self-assembled monolayers of 11-mercaptoundecanoic acid. The redox equilibria of the adsorbed tetraheme protein are studied by surface enhanced resonance Raman spectroscopy (SERRS). The quantitative analysis of the SERR spectra, which were measured as a function of the electrode potential, allows determining the redox potentials for the individual hemes of Cyt-c3. The values obtained of the redox potentials are compared with the data provided by NMR experiments and by molecular dynamics simulation studies of the electrostatically bound protein on a coated electrode. It is found that immobilisation causes substantial shifts of the redox potential, which would have an impact on the intramolecular electron flow.

  6. Ag electrode modified with polyhexamethylene biguanide stabilized silver nanoparticles: a new type of SERS substrates for detection of enzymatically generated thiocholine

    NASA Astrophysics Data System (ADS)

    Tepanov, A. A.; Nechaeva, N. L.; Prokopkina, T. A.; Kudrinskiy, A. A.; Kurochkin, I. N.; Lisichkin, G. V.

    2015-11-01

    The detection of thiocholine is one of the most widespread techniques for estimation of the cholinesterase activity - acetylcholinesterase and butyrylcholinesterase. Both cholinesterases can be inhibited by organophosphates and carbamates and accordingly can be considered for estimation of these pollutants in the environment. In the current work, SERS spectroscopy was applied for the thiocholine detection. The Ag electrodes modified with silver nanoparticles stabilized by polyhexamethylene biguanide were for the first time suggested as SERS-substrates for that purpose. Such electrodes can be applicable for SERS detection of submicromolar concentrations of thiocholine.

  7. Healable capacitive touch screen sensors based on transparent composite electrodes comprising silver nanowires and a furan/maleimide diels-alder cycloaddition polymer.

    PubMed

    Li, Junpeng; Liang, Jiajie; Li, Lu; Ren, Fengbo; Hu, Wei; Li, Juan; Qi, Shuhua; Pei, Qibing

    2014-12-23

    A healable transparent capacitive touch screen sensor has been fabricated based on a healable silver nanowire-polymer composite electrode. The composite electrode features a layer of silver nanowire percolation network embedded into the surface layer of a polymer substrate comprising an ultrathin soldering polymer layer to confine the nanowires to the surface of a healable Diels-Alder cycloaddition copolymer and to attain low contact resistance between the nanowires. The composite electrode has a figure-of-merit sheet resistance of 18 Ω/sq with 80% transmittance at 550 nm. A surface crack cut on the conductive surface with 18 Ω is healed by heating at 100 °C, and the sheet resistance recovers to 21 Ω in 6 min. A healable touch screen sensor with an array of 8×8 capacitive sensing points is prepared by stacking two composite films patterned with 8 rows and 8 columns of coupling electrodes at 90° angle. After deliberate damage, the coupling electrodes recover touch sensing function upon heating at 80 °C for 30 s. A capacitive touch screen based on Arduino is demonstrated capable of performing quick recovery from malfunction caused by a razor blade cutting. After four cycles of cutting and healing, the sensor array remains functional. PMID:25486240

  8. Zinc phthalocyanine and silver/gold nanoparticles incorporated MCM-41 type materials as electrode modifiers.

    PubMed

    Pal, Manas; Ganesan, Vellaichamy

    2009-11-17

    Mercaptopropyl functionalized ordered mesoporous silica spheres were prepared (MPS). Ag or Au nanoparticles (NPs) were anchored onto the MPS materials (Ag-MPS or Au-MPS). Further, zinc phthalocyanine (ZnPc) was adsorbed into the channels and surface (MPS-ZnPc, Ag-MPS-ZnPc, Au-MPS-ZnPc). Diffuse reflectance studies revealed the successful incorporation of Ag or Au NPs inside the silica spheres with and without ZnPc. TEM images showed the uniform distribution of Ag or Au NPs in the silica spheres of different size ranging from 4 to 22 nm or 6 to 31 nm, respectively. XRD pattern showed average crystallite particle size of 18 or 28 nm for Ag or Au NPs respectively which were reduced to 14 or 16 nm on introduction of ZnPc which oxidizes the metal NPs partially. Chemically modified electrodes were prepared by coating the colloidal solutions of the silica materials on the glassy carbon (GC) electrodes. Electrocatalytic reductions of O(2) and CO(2) at the modified electrodes were studied. The presence of Ag or Au NPs was found to increase the electrocatalytic efficiency of ZnPc toward O(2) reduction by 290% or 70% based on the current density measured at -0.35 V and toward CO(2) reduction by 150% or 120% based on the current density measured at -0.60 V respectively. Catalytic rate constants were increased 2-fold for O(2) reduction and 8-fold for CO(2) reduction due to Ag or Au NPs, respectively, which act as nanoelectrode ensembles. The synergic effect of ZnPc and metal NPs on the electrocatalytic reduction of O(2) is presented. PMID:19824690

  9. High-Curie-Temperature Pb(Zr,Ti)O3 Ceramic Actuator Cofired with Pure Silver Internal Electrodes

    NASA Astrophysics Data System (ADS)

    Ochiai, Hiroshi; Hayano, Syuji; Shoji, Kazuo; Kimura, Osamu; Maiwa, Hiroshi

    2008-07-01

    High-Curie temperature (Tc > 350 °C) lead zirconium titanate (PZT) ceramics cofired with low-cost pure silver (Ag) have been investigated for the manufacture of actuators for high-temperature applications. One percent of a low-firing additive, LiBiO2, was added to the conventionally calcined Pb (Zr0.52Ti0.48)O3 (PZT 52/48) powder and ground to 0.2 µm in average particle size, using yttrium toughened zirconia (YTZ) balls. PZT 52/48 ceramics fired at 850 °C showed a density = 7.9 g/cm3, an electromechanical coupling factor planar mode kp = 0.60, a piezoelectric constant d33 = 500 pm/V and a high Tc = 370 °C. PZT green sheets of 60 µm thickness with Ag metal paste were laminated and cofired at 850 °C. PZT ceramics cofired with Ag exhibited displacement corresponding to d33 = 363 pm/V; no Ag dispersion into PZT ceramics was detected. These results imply that the high-Tc cofired PZT ceramics with pure Ag internal electrodes are feasible for actuators in high-temperature applications.

  10. Composite Transparent Electrode of Graphene Nanowalls and Silver Nanowires on Micropyramidal Si for High-Efficiency Schottky Junction Solar Cells.

    PubMed

    Jiao, Tianpeng; Liu, Jian; Wei, Dapeng; Feng, Yanhui; Song, Xuefen; Shi, Haofei; Jia, Shuming; Sun, Wentao; Du, Chunlei

    2015-09-16

    The conventional graphene-silicon Schottky junction solar cell inevitably involves the graphene growth and transfer process, which results in complicated technology, loss of quality of the graphene, extra cost, and environmental unfriendliness. Moreover, the conventional transfer method is not well suited to conformationally coat graphene on a three-dimensional (3D) silicon surface. Thus, worse interfacial conditions are inevitable. In this work, we directly grow graphene nanowalls (GNWs) onto the micropyramidal silicon (MP) by the plasma-enhanced chemical vapor deposition method. By controlling growth time, the cell exhibits optimal pristine photovoltaic performance of 3.8%. Furthermore, we improve the conductivity of the GNW electrode by introducing the silver nanowire (AgNW) network, which could achieve lower sheet resistance. An efficiency of 6.6% has been obtained for the AgNWs-GNWs-MP solar cell without any chemical doping. Meanwhile, the cell exhibits excellent stability exposed to air. Our studies show a promising way to develop simple-technology, low-cost, high-efficiency, and stable Schottky junction solar cells. PMID:26308388

  11. Highly stable and flexible silver nanowire-graphene hybrid transparent conducting electrodes for emerging optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Lee, Donghwa; Lee, Hyungjin; Ahn, Yumi; Jeong, Youngjun; Lee, Dae-Young; Lee, Youngu

    2013-08-01

    A new AgNW-graphene hybrid transparent conducting electrode (TCE) was prepared by dry-transferring a chemical vapor deposition (CVD)-grown monolayer graphene onto a pristine AgNW TCE. The AgNW-graphene hybrid TCE exhibited excellent optical and electrical properties as well as mechanical flexibility. The AgNW-graphene hybrid TCE showed highly enhanced thermal oxidation and chemical stabilities because of the superior gas-barrier property of the graphene protection layer. Furthermore, the organic solar cells with the AgNW-graphene hybrid TCE showed excellent photovoltaic performance as well as superior long-term stability under ambient conditions.A new AgNW-graphene hybrid transparent conducting electrode (TCE) was prepared by dry-transferring a chemical vapor deposition (CVD)-grown monolayer graphene onto a pristine AgNW TCE. The AgNW-graphene hybrid TCE exhibited excellent optical and electrical properties as well as mechanical flexibility. The AgNW-graphene hybrid TCE showed highly enhanced thermal oxidation and chemical stabilities because of the superior gas-barrier property of the graphene protection layer. Furthermore, the organic solar cells with the AgNW-graphene hybrid TCE showed excellent photovoltaic performance as well as superior long-term stability under ambient conditions. Electronic supplementary information (ESI) available: Detailed electrical connection, mechanical flexibility, and chemical stability tests of the AgNW and AgNW-graphene hybrid TCEs are included. See DOI: 10.1039/c3nr02320f

  12. Void formation and roughening in slow fracture.

    PubMed

    Afek, Itai; Bouchbinder, Eran; Katzav, Eytan; Mathiesen, Joachim; Procaccia, Itamar

    2005-06-01

    Slow crack propagation in ductile, and in certain brittle materials, appears to take place via the nucleation of voids ahead of the crack tip due to plastic yields, followed by the coalescence of these voids. Postmortem analysis of the resulting fracture surfaces of ductile and brittle materials on the microm-mm and the nm scales, respectively, reveals self-affine cracks with anomalous scaling exponent zeta approximately = 0.8 in 3 dimensions and zeta approximately = 0.65 in 2 dimensions. In this paper we present an analytic theory based on the method of iterated conformal maps aimed at modelling the void formation and the fracture growth, culminating in estimates of the roughening exponents in 2 dimensions. In the simplest realization of the model we allow one void ahead of the crack, and address the robustness of the roughening exponent. Next we develop the theory further, to include two voids ahead of the crack. This development necessitates generalizing the method of iterated conformal maps to include doubly connected regions (maps from the annulus rather than the unit circle). While mathematically and numerically feasible, we find that the employment of the stress field as computed from elasticity theory becomes questionable when more than one void is explicitly inserted into the material. Thus further progress in this line of research calls for improved treatment of the plastic dynamics. PMID:16089840

  13. Multiscale surface roughening of commercial purity titanium during uniaxial tension

    SciTech Connect

    Panin, Alexey; Kazachenok, Marina Kozelskaya, Anna Sinyakova, Elena; Lider, Andrey Sklyarova, Elena

    2015-10-27

    The mechanisms of the surface roughening of the titanium specimens during uniaxial tension were demonstrated. By means of optical profilometry and electron backscattered diffraction it was shown that the formation of surface roughening is a multilevel process. The correlation between the density of slip in some grains, and grain rotation, and their displacement towards the free surface was investigated.

  14. Polymer-facilitated low temperature fusing of spray-coated silver nanowire networks as transparent top and bottom electrodes in small molecule organic photovoltaics (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-10-01

    Networks of silver nanowires (AgNWs) are promising candidates for transparent conducting electrodes in organic photovoltaics (OPV), as they achieve similar performance as the commonly used indium tin oxide (ITO) at lower cost and increased flexibility. The initial sheet resistance (Rs) of AgNW electrodes typically needs to be reduced by a post-annealing step (90 min@200 °C), being detrimental for processing on polymeric substrates. We present novel low temperature-based methods to integrate AgNWs in organic small molecule-based photovoltaics, either as transparent and highly conductive bottom-electrode or, for the first time, as spray-coated AgNW top-electrode. The bottom-electrodes are prepared by organic matrix assisted low-temperature fusing. Here, selected polymers are coated below the AgNWs to increase the interaction between NWs and substrate. In comparison to networks without these polymeric sublayers, the Rs is reduced by two orders of magnitude. AgNW top-electrodes are realized by dispersing modified high-quality AgNWs in inert solvents, which do not damage small molecule layers. Accordingly, our AgNW dispersion can be spray-coated onto all kind of OPV devices. Both bottom- and top-electrodes show a Rs of <11 Ω/ at >87 % transparency directly after spray-coating at very low substrate temperatures of <80 °C. We also demonstrate the implementation of our AgNW electrodes in organic solar cells. The corresponding devices show almost identical performance compared to organic solar cells exploiting ITO as bottom or thermally evaporated thin-metal as top-electrode.

  15. Organic-Stabilizer-Free Polyol Synthesis of Silver Nanowires for Electrode Applications.

    PubMed

    Sim, Hwansu; Bok, Shingyu; Kim, Bongsung; Kim, Minha; Lim, Guh-Hwan; Cho, Sung Min; Lim, Byungkwon

    2016-09-19

    The polyol reduction of a Ag precursor in the presence of an organic stabilizer, such as poly(vinylpyrrolidone), is a widely used method for the production of Ag nanowires (NWs). However, organic capping molecules introduce insulating layers around each NW. Herein we demonstrate that Ag NWs can be produced in high yield without any organic stabilizers simply by introducing trace amounts of NaCl and Fe(NO3 )3 during low-temperature polyol synthesis. The heterogeneous nucleation and growth of Ag NWs on initially formed AgCl particles, combined with oxidative etching of unwanted Ag nanoparticles, resulted in the selective formation of long NWs with an average length of about 40 μm in the absence of a capping or stabilizing effect provided by surface-adsorbing molecules. These organic-stabilizer-free Ag NWs were directly used for the fabrication of high-performance transparent or stretchable electrodes without a complicated process for the removal of capping molecules from the NW surface. PMID:27571578

  16. Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes.

    PubMed

    Kim, Seong Heon; Choi, Woon Ih; Kim, Kwang Hee; Yang, Dae Jin; Heo, Sung; Yun, Dong-Jin

    2016-01-01

    The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases. PMID:27620453

  17. Force constants and bond polarizabilities of thiocyanate ion adsorbed on the silver electrode as interpreted from the surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Huang, Yi; Wu, Guozhen

    1989-01-01

    The surface enhanced Raman spectra of the thiocyanate ion is studied in two ways. First, normal mode analysis is employed to determine the force constants of the adsorbed thiocyanate ion. The result shows that the force constant for the CN bond becomes larger while that for the SC bond smaller in the adsorbed state. The adatom model with an effective silver mass of 0.1 mAg ( mAg being the mass of the silver atom) is adequate for the analysis. This implies that the silver adatom is bound to the bulk electrode surface. The adsorption is also shown to be physical. Second, the SER intensifies are analyzed to obtain the molecular polarizability derivatives. The result shows that the polarizability derivative of the CN stretching motion is most responsive to the applied voltage. The polarizability derivative of the SC stretching motion is much smaller than that of the CN bond as compared in the solution. This conclusion is attributed to the adsorption center at the sulfur atom. In general, molecular polarizability derivatives are functions of the frequencies of the exciting lasers and the applied voltages on the electrode.

  18. Electrochemical Investigation of Coenzyme Q10 on Silver Electrode in Ethanol Aqueous Solution and Its Determination Using Differential Pulse Voltammetry.

    PubMed

    Li, Dan; Deng, Wei; Xu, Hu; Sun, Yinxing; Wang, Yuhong; Chen, Shouhui; Ding, Xianting

    2016-08-01

    The electrochemistry reduction of coenzyme Q10 (CoQ10) on silver electrodes has been investigated in mixed solvent containing 95 vol. % ethanol and 5 vol. % water. A combination of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) is employed to explore the mechanism of redox processes of CoQ10 in the presence and absence of oxygen, respectively. It has been proved that the redox reaction of CoQ10 is highly dependent on the oxygen in the solution compared with that of CoQ0, which may be attributed to the isoprenoid side chain effect of CoQ10 Moreover, the effects of experimental variables such as electrolyte component, pH, temperature, and sonication time on the amperometric and potentiometric responses of CoQ10 are presented. The differential pulse voltammetry method has been developed for the quantification of the CoQ10 in the complex samples. Under the optimum conditions, the method is linear over the concentration range of 1.00 × 10(-7) to 1.00 × 10(-3) mol/L (8.63 × 10(-2) to 8.63 × 10(2) mg/kg). The limit of detection (3σ/k) is 3.33 × 10(-8) mol/L (2.88 × 10(-2) mg/kg). The recoveries of the spiked samples are between 91% and 108%. The presented method can be applied to the analysis of CoQ10 in real samples without any pretreatment. PMID:27094091

  19. Extraction of Silver by Glucose.

    PubMed

    Baksi, Ananya; Gandi, Mounika; Chaudhari, Swathi; Bag, Soumabha; Gupta, Soujit Sen; Pradeep, Thalappil

    2016-06-27

    Unprecedented silver ion leaching, in the range of 0.7 ppm was seen when metallic silver was heated in water at 70 °C in presence of simple carbohydrates, such as glucose, making it a green method of silver extraction. Extraction was facilitated by the presence of anions, such as carbonate and phosphate. Studies confirm a two-step mechanism of silver release, first forming silver ions at the metal surface and later complexation of ionic silver with glucose; such complexes have been detected by mass spectrometry. Extraction leads to microscopic roughening of the surface making it Raman active with an enhancement factor of 5×10(8) . PMID:27119514

  20. Effect of silver or copper middle layer on the performance of palladium modified nickel foam electrodes in the 2-chlorobiphenyl dechlorination.

    PubMed

    He, Zhiqiao; Sun, Junjun; Wei, Jie; Wang, Qiong; Huang, Chengxiang; Chen, Jianmeng; Song, Shuang

    2013-04-15

    To enhance the activity of chemi-deposited palladium/nickel foam (Pd/Ni) electrodes used for an electrochemical dechlorination process, silver or copper was deposited electrochemically onto the nickel foam substrate (to give Ag/Ni or Cu/Ni) before the chemical deposition of palladium. The physicochemical properties of the resulting materials (Pd/Ni, Pd/Ag/Ni and Pd/Cu/Ni) were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their electrochemical catalytic activities were evaluated by monitoring the electrochemical dechlorination of 2-chlorobiphenyl (2-CB) in strongly alkaline methanol/water solution. The results show that the Pd/Ag/Ni and Pd/Cu/Ni electrodes had consistently higher electrocatalytic activities and current efficiencies (CEs) compared with the untreated Pd/Ni electrode. The Pd/Ag/Ni electrode exhibited the highest activity. The dechlorination was also studied as a function of Pd loading, the Ag or Cu interlayer loadings, and the current density. The Pd loading and the interlayer loadings both had positive effects on the dechlorination reaction. Increasing the current density increased the reaction rate but reduced the CE. The improvement of the electrocatalytic activities of the Pd/Ni electrode by applying the interlayer of Ag or Cu resulted from the enlargement of the effective surface area of the electrode and the adjustment of the metal-H bond energy to the appropriate value, as well as the effective adsorption of 2-CB on Ag. Moreover, the high catalytic activity of the Pd/Ag/Ni electrode was maintained after six successive cyclic experiments, whereas Pd/Cu/Ni electrodes deactivate severely under the same conditions. PMID:23454456

  1. Determination of ultra-trace amounts of silver in water by differential pulse anodic stripping voltammetry using a new modified carbon paste electrode.

    PubMed

    El-Mai, Hafida; Espada-Bellido, Estrella; Stitou, Mostafa; García-Vargas, Manuel; Galindo-Riaño, Maria Dolores

    2016-05-01

    A highly sensitive and selective new procedure for the determination of silver in aqueous media was developed using a modified carbon paste electrode (MCPE) by differential pulse anodic stripping voltammetry (DPASV). The modified electrode was based on the incorporation of 2-hydroxybenzaldehyde benzoylhydrazone (2-HBBH) in the carbon paste electrode. Silver ions were preconcentrated on the modified electrode at open-circuit by complexation with the ligand and reduced to zero valent at a potential of 0V, and followed by the reoxidation of adsorbed ions onto the electrode by scanning the potential in a positive direction. The oxidation peak of Ag(I) was observed at 0.2V (versus Ag/AgCl). The analysis of Ag(I) was carried out in a cell containing the sample solution (20mL) buffered by 0.1molL(-1) K2HPO4/NaOH at pH 5.5 in aqueous solution and nitric acid (pH 1) in real water samples. The optimum conditions for the analysis of silver include a reduction potential of 0V and a pulse amplitude of 100mV, among others. The optimum carbon paste composition was found to be 14.1% (w/w) 2-HBBH, 56.2% (w/w) graphite powder and 29.7% (w/w) paraffin oil. Differential pulse anodic stripping voltammetric response was used as the analytical signal. Under the selected conditions, the voltammetric signal was proportional to the Ag(I) concentration in the range of 0.001-100μgL(-1) with favorable limits of detection and quantification of 1.1ngL(-1) and 3.7ngL(-1) after 3min of accumulation time, respectively. By increasing the accumulation time to 10min, detection and quantification limits can be further improved up to 0.1ngL(-1) and 0.34ngL(-1), respectively. In addition, the results showed a highly reproducible procedure showing a relative standard deviation of 1.5% for 12 replicate measurements. Many coexisting metal ions were investigated and very few interferences were found on the determination of Ag(I). The proposed method was validated using certified reference estuarine waters

  2. Roughening of Polyimide Surface for Inkjet Printing by Plasma Etching Using the Polyimide Masked with Polystyrene Nanosphere Array.

    PubMed

    Mun, Mu Kyeom; Park, Jin Woo; Ahn, Jin Ho; Kim, Ki Kang; Yeom, Geun Young

    2015-10-01

    Two key conditions are required for the application of fine-line inkjet printing onto a flexible substrate such as polyimide (PI): linewidth control during the inkjetting process, and a strong adhesion of the polyimide surface to the ink after the ink solidifies. In this study, the properties of a polyimide surface that was roughened through etching in a He/SF6 plasma, using a polystyrene nanosphere array as the etch mask, were investigated. The near-atmospheric-pressure plasma system of the He/SF6 plasma that was used exhibits two notable properties in this context: similar to an atmospheric-pressure plasma system, it can easily handle inline substrate processing; and, similar to a vacuum system, it can control the process gas environment. Through the use of plasma etching, the polyimide surface masked the 120-nm-diameter polystyrene nanospheres, thereby forming a roughened nanoscale polyimide surface. This surface exhibited not only a greater hydrophobicity--with a contact angle of about 150° for water and about 30° for silver ink, indicating better silver linewidth control during the silver inkjetting process--but also a stronger adhesion to the silver ink sprayed onto it when compared with the flat polyimide surface. PMID:26726483

  3. Thickness- and Particle-Size-Dependent Electrochemical Reduction of Carbon Dioxide on Thin-Layer Porous Silver Electrodes.

    PubMed

    Zhang, Lin; Wang, Zhiyong; Mehio, Nada; Jin, Xianbo; Dai, Sheng

    2016-03-01

    The electrochemical reduction of CO2 can not only convert it back into fuels, but is also an efficient manner to store forms of renewable energy. Catalysis with silver is a possible technology for CO2 reduction. We report that in the case of monolithic porous silver, the film thickness and primary particle size of the silver particles, which can be controlled by electrochemical growth/reduction of AgCl film on silver substrate, have a strong influence on the electrocatalytic activity towards CO2 reduction. A 6 μm thick silver film with particle sizes of 30-50 nm delivers a CO formation current of 10.5 mA cm(-2) and a mass activity of 4.38 A gAg (-1) at an overpotential of 0.39 V, comparable to levels achieved with state-of-the-art gold catalysts. PMID:26822587

  4. VOLTAMMETRIC MEMBRANE CHLORINE DIOXIDE ELECTRODE

    EPA Science Inventory

    A voltammetric membrane electrode system has been modified and applied to the in situ measurement of chlorine dioxide. The electrode system consisted of a gold cathode, a silver/silver chloride reference electrode, and a gold counter electrode. Different membrane materials were t...

  5. Kinetic Roughening and Bifurcations in Reaction - Systems

    NASA Astrophysics Data System (ADS)

    Provatas, Nikolas

    1995-01-01

    We study the dynamics of two reaction-diffusion phenomena driven by chemical activation and thermal dissipation and evolving, respectively, on a randomly distributed or continuous medium. The first system describes the process of slow combustion of a randomly distributed reactant. It is studied by a phase-field model built up from first principles and describes the evolution of thermal and reactant concentration fields. Our combustion model incorporates thermal diffusion, activation and dissipation. We examine it in a manner which makes a connection between the propagation of combustion fronts, their kinetic roughening and the percolation transition. In so doing, we examine slow combustion in the context phase transitions. The second system describes propagation of reaction fronts arising in transformations obeying the Arrhenius law of chemical reactions. It too is modelled by a set of phase-field equations describing the dynamics of both thermal and concentration fields. A typical example of this transformation is the crystallization of an amorphous material. In addition to the features of our combustion model, this model also incorporated a realistic treatment of mass diffusion. Front propagation of our model is shown to undergo period doubling bifurcations as one varies the background temperature at which the system is maintained. The signature of these bifurcations is the same as those of the logistics map. We study how the bifurcation structure changes as a function mass diffusion, focusing on changes of the background temperature for which period doubling first emerges. This temperature is the most easily obtained experimentally.

  6. Bioinspired assembly of surface-roughened nanoplatelets.

    PubMed

    Lin, Tzung-Hua; Huang, Wei-Han; Jun, In-Kook; Jiang, Peng

    2010-04-15

    Here we report a novel electrophoretic deposition technology for assembling surface-roughened inorganic nanoplatelets into ordered multilayers that mimic the brick-and-mortar nanostructure found in the nacreous layer of mollusk shells. A thin layer of sol-gel silica is coated on smooth gibbsite nanoplatelets in order to increase the surface roughness to mimic the asperity of aragonite platelets found in nacres. To avoid the severe cracking caused by the shrinkage of sol-gel silica during drying, polyelectrolyte polyethyleneimine is used to reverse the surface charge of silica-coated-gibbsite nanoplatelets and increase the adherence and strength of the electrodeposited films. Polymer nanocomposites can then be made by infiltrating the interstitials of the aligned nanoplatelet multilayers with photocurable monomer followed by photopolymerization. The resulting self-standing films are highly transparent and exhibit nearly three times higher tensile strength and one-order-of-magnitude higher toughness than those of pure polymer. The measured tensile strength agrees with that predicted by a simple shear lag model. PMID:20102769

  7. Surface roughened zirconia: towards hydrothermal stability.

    PubMed

    Camposilvan, Erik; Flamant, Quentin; Anglada, Marc

    2015-07-01

    Surface roughness is needed in several yttria-stabilized zirconia components used in restorative dentistry for osseointegration or adhesion purposes. This can be achieved by different treatments, which may also modify the microstructure of the surface. Among them, sandblasting and chemical etching are widely used, but their effect on hydrothermal aging of zirconia is not fully understood. In the present work, the zirconia long-term stability of rough surfaces prepared by these techniques is analyzed and a method is proposed for preventing hydrothermal aging while maintaining the original surface appearance and mechanical properties. The method involves pressure infiltration of a Cerium salt solution on the roughened surfaces followed by a thermal treatment. The solution, trapped by surface defects and small pores, is decomposed during thermal treatment into Cerium oxide, which is diffused at high temperature, obtaining Ce co-doping in the near-surface region. In addition, the microstructural changes induced in the near-surface by sandblasting or chemical etching are removed by the thermal treatment together with surface defects. No color modification was observed and the final roughness parameters were in the range of existing implants of proved good osseointegration. The aging resistance of Ce co-doped materials was strongly enhanced, showing the absence of aging after artificial degradation, increasing in this way the surface mechanical integrity. The proposed treatment is easily applicable to the current manufacturing procedures of zirconia dental posts, abutments, crowns and dentures, representing a solution to hydrothermal aging in these and other biomedical applications. PMID:25867636

  8. Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application.

    PubMed

    Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

    2015-11-01

    A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H2O2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R(2) = 0.990). This sensor has been applied to detect the trace H2O2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility. PMID:26469539

  9. Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application

    NASA Astrophysics Data System (ADS)

    Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

    2015-11-01

    A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H2O2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R2 = 0.990). This sensor has been applied to detect the trace H2O2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility.

  10. Sensitivities of Key Parameters in the Preparation of Silver/Silver Chloride Electrodes Used in Harned Cell Measurements of pH

    PubMed Central

    Brewer, Paul J.; Stoica, Daniela; Brown, Richard J. C.

    2011-01-01

    A questionnaire was completed by fourteen world leading national metrology institutes to study the influence of several variables in the preparation of Ag/AgCl electrodes on the accuracy of Harned cell measurements of pH. The performance of each institute in the last decade has been assessed based on their results in eight key comparisons, organized by the Bureau International des Poids et Measures Consultative Committee for Amount of Substance, involving the measurement of pH of phosphate, phthalate, carbonate, borate and tetroxalate buffer solutions. The performance of each laboratory has been correlated to the results of the questionnaire to determine the critical parameters in the preparation of Ag/AgCl electrodes and their sensitivities with respect to the accuracy of pH measurement. This study reveals that the parameters most closely correlated to performance in comparisons are area of electrode wire exposed to the electrolyte, diameter and porosity of the Ag sphere prior to anodisation, amount of Ag converted to AgCl during anodisation, stability times employed for electrodes to reach equilibrium in solution prior to measurement, electrode rejection criteria employed and purity of reagents. PMID:22164063

  11. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics.

    PubMed

    Selzer, Franz; Weiss, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-02-14

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □(-1) at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode. PMID:25584968

  12. Ultrasensitive detection of lead ion sensor based on gold nanodendrites modified electrode and electrochemiluminescent quenching of quantum dots by electrocatalytic silver/zinc oxide coupled structures.

    PubMed

    Li, Meng; Kong, Qingkun; Bian, Zhaoquan; Ma, Chao; Ge, Shenguang; Zhang, Yan; Yu, Jinghua; Yan, Mei

    2015-03-15

    A signal-off electrochemiluminescence (ECL) DNA sensor based on gold nanodendrites (Au NDs) modified indium tin oxide (ITO) electrode for the detection of lead ion (Pb(2+)) was developed. Well-defined Au NDs were prepared on ITO electrode using low-potential synthesis, assisted by ethylenediamine. Based on Pb(2+)-specific deoxyribozyme, the silver/zinc oxide (Ag/ZnO) with coupled structure, prepared by one-pot method, was close to the surface of the electrode to catalyze the reduction of part of H2O2, the coreactant for cathodic ECL emission, leading to a decrease of ECL intensity. In addition, taking advantage of the larger surface area to capture a large amount of capture probe as well as excellent conductivity of Au NDs, the sensor could detect Pb(2+) quantitatively in a wider range, and performed excellent selectivity. Furthermore, such simple and sensitive DNA sensor was successfully applied for the detection of Pb(2+) in lake water and human serum samples, respectively. PMID:25461155

  13. Investigation of protein FTT1103 electroactivity using carbon and mercury electrodes. Surface-inhibition approach for disulfide oxidoreductases using silver amalgam powder.

    PubMed

    Večerková, Renata; Hernychová, Lenka; Dobeš, Petr; Vrba, Jiří; Josypčuk, Bohdan; Bartošík, Martin; Vacek, Jan

    2014-06-01

    Recently, it was shown that electrochemical methods can be used for analysis of poorly water-soluble proteins and for study of their structural changes and intermolecular (protein-ligand) interactions. In this study, we focused on complex electrochemical investigation of recombinant protein FTT1103, a disulfide oxidoreductase with structural similarity to well described DsbA proteins. This thioredoxin-like periplasmic lipoprotein plays an important role in virulence of bacteria Francisella tularensis. For electrochemical analyses, adsorptive transfer (ex situ) square-wave voltammetry with pyrolytic graphite electrode, and alternating-current voltammetry and constant-current chronopotentiometric stripping analysis with mercury electrodes, including silver solid amalgam electrode (AgSAE) were used. AgSAE was used in poorly water-soluble protein analysis for the first time. In addition to basic redox, electrocatalytic and adsorption/desorption characterization of FTT1103, electrochemical methods were also used for sensitive determination of the protein at nanomolar level and study of its interaction with surface of AgSA microparticles. Proposed electrochemical protocol and AgSA surface-inhibition approach presented here could be used in future for biochemical studies focused on proteins associated with membranes as well as on those with disulfide oxidoreductase activity. PMID:24856508

  14. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  15. Capillary flow of solder on chemically roughened PWB surfaces

    SciTech Connect

    Hosking, F.M.; Stevenson, J.O.; Yost, F.G.

    1996-02-01

    The Center for Solder Science and Technology at Sandia National Laboratories has developed a solderability test for evaluating fundamental solder flow over PWB (printed wiring boards) surface finishes. The work supports a cooperative research and development agreement between Sandia, the National Center for Manufacturing Sciences (NCMS), and several industrial partners. An important facet of the effort involved the ``engineering`` of copper surfaces through mechanical and chemical roughening. The roughened topography enhances solder flow, especially over very fine features. In this paper, we describe how etching with different chemical solutions can affect solder flow on a specially designed ball grid array test vehicle (BGATV). The effects of circuit geometry, solution concentration, and etching time are discussed. Surface roughness and solder flow data are presented to support the roughening premise. Noticeable improvements in solder wettability were observed on uniformly etched surfaces having relatively steep peak-to-valley slopes.

  16. A novel paper-based device coupled with a silver nanoparticle-modified boron-doped diamond electrode for cholesterol detection.

    PubMed

    Nantaphol, Siriwan; Chailapakul, Orawon; Siangproh, Weena

    2015-09-01

    A novel paper-based analytical device (PAD) coupled with a silver nanoparticle-modified boron-doped diamond (AgNP/BDD) electrode was first developed as a cholesterol sensor. The AgNP/BDD electrode was used as working electrode after modification by AgNPs using an electrodeposition method. Wax printing was used to define the hydrophilic and hydrophobic areas on filter paper, and then counter and reference electrodes were fabricated on the hydrophilic area by screen-printing in house. For the amperometric detection, cholesterol and cholesterol oxidase (ChOx) were directly drop-cast onto the hydrophilic area, and H2O2 produced from the enzymatic reaction was monitored. The fabricated device demonstrated a good linearity (0.39 mg dL(-1) to 270.69 mg dL(-1)), low detection limit (0.25 mg dL(-1)), and high sensitivity (49.61 μA mM(-1) cm(-2)). The precision value for ten replicates was 3.76% RSD for 1 mM H2O2. In addition, this biosensor exhibited very high selectivity for cholesterol detection and excellent recoveries for bovine serum analysis (in the range of 99.6-100.8%). The results showed that this new sensing platform will be an alternative tool for cholesterol detection in routine diagnosis and offers the advantages of low sample/reagent consumption, low cost, portability, and short analysis time. PMID:26388372

  17. Multiplexed enzyme-free electrochemical immunosensor based on ZnO nanorods modified reduced graphene oxide-paper electrode and silver deposition-induced signal amplification strategy.

    PubMed

    Sun, Guoqiang; Zhang, Lina; Zhang, Yan; Yang, Hongmei; Ma, Chao; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

    2015-09-15

    Herein, an origami multiplexed enzyme-free electrochemical (EC) immunodevice is developed for the first time. Typically, ZnO nanorods (ZNRs) modified reduced graphene oxide (rGO)-paper electrode is used as a sensor platform, in which rGO improves the electronic transmission rate and ZNRs provide abundant sites for capture probes binding. Furthermore, by combining the large surface area of rGO and high catalytic activity of bovine serum protein (BSA)-stabilized silver nanoparticles (Ag@BSA) toward H2O2 reduction, rGO/Ag@BSA composites can be used as an excellent signal labels. The current signal is generated from the reduction of H2O2 and further amplified by a subsequent signal labels-promoted deposition of silver. Under optimal conditions, the proposed immunoassays exhibit excellent precision, high sensitivity and a wide linear range of 0.002-120 mIU mL(-1) for human chorionic gonadotropin, 0.001-110 ng mL(-1) for prostate-specific antigen, and 0.001-100 ng mL(-1) for carcinoembryonic antigen. The results for real sample analysis demonstrate that the newly constructed immunosensor arrays provide a simple and cost-effective method for clinical applications. PMID:25884731

  18. Silver front electrode grids for ITO-free all printed polymer solar cells with embedded and raised topographies, prepared by thermal imprint, flexographic and inkjet roll-to-roll processes.

    PubMed

    Yu, Jong-Su; Kim, Inyoung; Kim, Jung-Su; Jo, Jeongdai; Larsen-Olsen, Thue T; Søndergaard, Roar R; Hösel, Markus; Angmo, Dechan; Jørgensen, Mikkel; Krebs, Frederik C

    2012-09-28

    Semitransparent front electrodes for polymer solar cells, that are printable and roll-to-roll processable under ambient conditions using different approaches, are explored in this report. The excellent smoothness of indium-tin-oxide (ITO) electrodes has traditionally been believed to be difficult to achieve using printed front grids, as surface topographies accumulate when processing subsequent layers, leading to shunts between the top and bottom printed metallic electrodes. Here we demonstrate how aqueous nanoparticle based silver inks can be employed as printed front electrodes using several different roll-to-roll techniques. We thus compare hexagonal silver grids prepared using either roll-to-roll inkjet or roll-to-roll flexographic printing. Both inkjet and flexo grids present a raised topography and were found to perform differently due to only the conductivity of the obtained silver grid. The raised topographies were compared with a roll-to-roll thermally imprinted grid that was filled with silver in a roll-to-roll process, thus presenting an embedded topography. The embedded grid and the flexo grid were found to perform equally well, with the flexographic technique currently presenting the fastest processing and the lowest silver use, whereas the embedded grid presents the maximally achievable optical transparency and conductivity. Polymer solar cells were prepared in the same step, using roll-to-roll slot-die coating of zinc oxide as the electron transport layer, poly-3-hexylthiophene:phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) as the active layer and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the top electrode, along with a flat bed screen printed silver grid. The power conversion efficiency (PCE) obtained for large area devices (6 cm(2)) was 1.84%, 0.79% and 1.72%, respectively, for thermally imprinted, inkjet and flexographic silver grids, tested outside under the real sun. Central to all three approaches was that they

  19. Silver-iron batteries

    NASA Astrophysics Data System (ADS)

    Lindstroem, O.

    1980-04-01

    Production methods for iron electrodes were studied. It was found that a sintering temperature of 700 C gave the best strength and capacity. Production methods and additions for silver electrodes were also studied. The capacity of the produced iron and silver electrodes were 1100 mAh/cu cm. Different separators were investigated. Cellophane I and II from Du Pont was found to be the best. In tests open cells achieved 60 percent of the calculated capacity. In order to minimize the increase of the pressure in closed cells different additions to the electrodes were studied.

  20. Preparation of flexible organic solar cells with highly conductive and transparent metal-oxide multilayer electrodes based on silver oxide.

    PubMed

    Yun, Jungheum; Wang, Wei; Bae, Tae Sung; Park, Yeon Hyun; Kang, Yong-Cheol; Kim, Dong-Ho; Lee, Sunghun; Lee, Gun-Hwan; Song, Myungkwan; Kang, Jae-Wook

    2013-10-23

    We report that significantly more transparent yet comparably conductive AgOx films, when compared to Ag films, are synthesized by the inclusion of a remarkably small amount of oxygen (i.e., 2 or 3 atom %) in thin Ag films. An 8 nm thick AgOx (O/Ag=2.4 atom %) film embedded between 30 nm thick ITO films (ITO/AgOx/ITO) achieves a transmittance improvement of 30% when compared to a conventional ITO/Ag/ITO electrode with the same configuration by retaining the sheet resistance in the range of 10-20 Ω sq(-1). The high transmittance provides an excellent opportunity to improve the power-conversion efficiency of organic solar cells (OSCs) by successfully matching the transmittance spectral range of the electrode to the optimal absorption region of low band gap photoactive polymers, which is highly limited in OSCs utilizing conventional ITO/Ag/ITO electrodes. An improvement of the power-conversion efficiency from 4.72 to 5.88% is achieved from highly flexible organic solar cells (OSCs) fabricated on poly(ethylene terephthalate) polymer substrates by replacing the conventional ITO/Ag/ITO electrode with the ITO/AgOx/ITO electrode. This novel transparent electrode can facilitate a cost-effective, high-throughput, room-temperature fabrication solution for producing large-area flexible OSCs on heat-sensitive polymer substrates with excellent power-conversion efficiencies. PMID:24060352

  1. Preliminary flight prototype silver ion monitoring system

    NASA Technical Reports Server (NTRS)

    Brady, J.

    1974-01-01

    The design, fabrication, and testing of a preliminary flight prototype silver ion monitoring system based on potentiometric principles and utilizing a solid-state silver sulfide electrode paired with a pressurized double-junction reference electrode housing a replaceable electrolyte reservoir is described. The design provides automatic electronic calibration utilizing saturated silver bromide solution as a silver ion standard. The problem of loss of silver ion from recirculating fluid, its cause, and corrective procedures are reported. The instability of the silver sulfide electrode is discussed as well as difficulties met in implementing the autocalibration procedure.

  2. The investigation of electrolytic surface roughening for PCB copper foil

    NASA Astrophysics Data System (ADS)

    Lee, Shuo-Jen; Liu, Chao-Kai

    2013-10-01

    This study is the application of the principle of electrochemical. The anodic dissolution has no concentration polarization. Hence, electrolyte life is substantially increased. The waste copper is high in ion concentration with a recovery value. As compared with the current PCB chemical pre-treatment method, it may have advantages of cost-saving, improvement of overall efficiency, reduction of production costs and reduction of the amount of waste generated. In the development of the copper foil for electrochemical roughening process, the use of electrolysis reaction affects the copper surface dissolution to form a unique bump coarsening. It will increase in the surface area of the copper foil to improve dry film solder mask and the adhesion between the copper surfaces. Four electrolytes, two neutral salts and two acids, were selected to explore the best of the electrolytic roughening parameters of temperature, time and voltage. The surface roughness and the surface morphology of the copper foil were measured before and after the electrolytic surface roughening. Finally, after repeated experiments, electrolytes A and B copper generates obvious inter-granular corrosion, resulting in a rough surface similar to the chemical pre-treatment. On the other hands, the surface morphology resulted from electrolytes C and D appears more like pitting. Both electrolytic could generate surface roughness of Ra 0.3 um roughened copper surface higher than industrial standard.

  3. A dielectrophoretic chip with a roughened metal surface for on-chip surface-enhanced Raman scattering analysis of bacteria

    PubMed Central

    Cheng, I-Fang; Lin, Chi-Chang; Lin, Dong-Yi; Chang, Hsien-Chang

    2010-01-01

    We present an analysis of the results of in situ surface-enhanced Raman scattering (SERS) of bacteria using a microfluidic chip capable of continuously sorting and concentrating bacteria via three-dimensional dielectrophoresis (DEP). Microchannels were made by sandwiching DEP microelectrodes between two glass slides. Avoiding the use of a metal nanoparticle suspension, a roughened metal surface is integrated into the DEP-based microfluidic chip for on-chip SERS detection of bacteria. On the upper surface of the slide, a roughened metal shelter was settled in front of the DEP concentrator to enhance Raman scattering. Similarly, an electrode-patterned bottom layer fabricated on a thin cover-slip was used to reduce fluorescence noise from the glass substrate. Gram positive (Staphylococcus aureus) and Gram negative (Pseudomonas aeruginosa) bacteria were effectively distinguished in the SERS spectral data. Staphylococcus aureus (concentration of 106 CFU∕ml) was continuously separated and concentrated via DEP out of a sample of blood cells. At a flow rate of 1 μl∕min, the bacteria were highly concentrated at the roughened surface and ready for on-chip SERS analysis within 3 min. The SERS data were successfully amplified by one order of magnitude and analyzed within a few minutes, resulting in the detection of signature peaks of the respective bacteria. PMID:20806000

  4. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE. PMID:27149372

  5. Electrocatalytic simultaneous determination of ascorbic acid, uric acid and L-Cysteine in real samples using quercetin silver nanoparticles-graphene nanosheets modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Zare, Hamid R.; Jahangiri-Dehaghani, Fahime; Shekari, Zahra; Benvidi, Ali

    2016-07-01

    By immobilizing of quercetin at the surface of a glassy carbon electrode modified with silver nanoparticles and graphene nanosheets (Q-AgNPs-GNs-GCE) a new sensor has been fabricated. The cyclic voltammogram of Q-AgNPs-GNs-GCE shows a stable redox couple with surface confined characteristics. Q-AgNPs-GNs-GCE demonstrated a high catalytic activity for L-Cysteine (L-Cys) oxidation. Results indicated that L-Cys peak potential at Q-AgNPs-GNs-GCE shifted to less positive values compared to GNs-GCE or AgNPs-GCE. Also, the kinetic parameters such as the electron transfer coefficient,, and the heterogeneous electron transfer rate constant, k‧, for the oxidation of L-Cys at the Q-AgNPs-GNs-GCE surface were estimated. In differential pulse voltammetric determination, the detection limit of L-Cys was obtained 0.28 μM, and the calibration plots were linear within two ranges of 0.9-12.4 μM and 12.4-538.5 μM of L-Cys. Also, the proposed modified electrode is used for the simultaneous determinations of ascorbic acid (AA), uric acid (UA), and L-Cys. Finally, this study has demonstrated the practical analytical utility of the sensor for determination of AA in vitamin C tablet, L-Cys in a milk sample and UA in a human urine sample.

  6. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    NASA Astrophysics Data System (ADS)

    Heo, Gaeun; Pyo, Kyoung-Hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-05-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11.

  7. Critical Role of Diels-Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer.

    PubMed

    Heo, Gaeun; Pyo, Kyoung-Hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-01-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels-Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching-releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11. PMID:27140436

  8. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    PubMed Central

    Heo, Gaeun; Pyo, Kyoung-hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-01-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11. PMID:27140436

  9. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-01-01

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87

  10. Smoothing of ultrathin silver films by transition metal seeding

    NASA Astrophysics Data System (ADS)

    Anders, André; Byon, Eungsun; Kim, Dong-Ho; Fukuda, Kentaro; Lim, Sunnie H. N.

    2006-11-01

    The nucleation and coalescence of silver islands on coated glass was investigated by in situ measurements of the sheet resistance. Sub-monolayer amounts of niobium and other transition metals were deposited prior to the deposition of silver. It was found that in some cases, the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing or roughening effects by the presence of the transition metal can be explained by kinetically limited transition metal islands growth and oxidation, followed by defect-dominated nucleation of silver.

  11. Fast and low-temperature sintering of silver complex using oximes as a potential reducing agent for solution-processible, highly conductive electrodes

    NASA Astrophysics Data System (ADS)

    Yoo, Ji Hoon; Han, Dae Sang; Park, Su Bin; Chae, Jangwoo; Kim, Ji Man; Kwak, Jeonghun

    2014-11-01

    Highly conductive, solution-processed silver thin-films were obtained at a low sintering temperature of 100 °C in a short sintering time of 10 min by introducing oximes as a potential reductant for silver complex. The thermal properties and reducibility of three kinds of oximes, acetone oxime, 2-butanone oxime, and one dimethylglyoxime, were investigated as a reducing agent, and we found that the thermal decomposition product of oximes (ketones) accelerated the conversion of silver complex into highly conductive silver at low sintering temperature in a short time. Using the acetone oxime, the silver thin-film exhibited the lowest surface resistance (0.91 Ω sq-1) compared to those sing other oximes. The silver thin-film also showed a high reflectance of 97.8%, which is comparable to evaporated silver films. We also demonstrated inkjet printed silver patterns with the oxime-added silver complex inks.

  12. Plasma jet electrode has longer operating life

    NASA Technical Reports Server (NTRS)

    Gracey, C. M.

    1967-01-01

    Water-cooled, silver-infiltrated tungsten electrode has twice the operating lifetime of the pure tungsten electrode used in plasma jet generators. This electrode reduces the erosion rate, ensures excellent heat transfer, and reduces thermal stresses.

  13. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  14. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  15. Metal-oxide thin-film transistor-based pH sensor with a silver nanowire top gate electrode

    NASA Astrophysics Data System (ADS)

    Yoo, Tae-Hee; Sang, Byoung-In; Wang, Byung-Yong; Lim, Dae-Soon; Kang, Hyun Wook; Choi, Won Kook; Lee, Young Tack; Oh, Young-Jei; Hwang, Do Kyung

    2016-04-01

    Amorphous InGaZnO (IGZO) metal-oxide-semiconductor thin-film transistors (TFTs) are one of the most promising technologies to replace amorphous and polycrystalline Si TFTs. Recently, TFT-based sensing platforms have been gaining significant interests. Here, we report on IGZO transistor-based pH sensors in aqueous medium. In order to achieve stable operation in aqueous environment and enhance sensitivity, we used Al2O3 grown by using atomic layer deposition (ALD) and a porous Ag nanowire (NW) mesh as the top gate dielectric and electrode layers, respectively. Such devices with a Ag NW mesh at the top gate electrode rapidly respond to the pH of solutions by shifting the turn-on voltage. Furthermore, the output voltage signals induced by the voltage shifts can be directly extracted by implantation of a resistive load inverter.

  16. Co-Percolating Graphene-Wrapped Silver Nanowire Network for High Performance, Highly Stable, Transparent Conducting Electrodes

    SciTech Connect

    Chen, Ruiyi; Das, Suprem R; Jeong, Changwook; Khan, Mohammad Ryyan; Janes, David B; Alam, Muhammad A

    2013-04-25

    Transparent conducting electrodes (TCEs) require high transparency and low sheet resistance for applications in photovoltaics, photodetectors, flat panel displays, touch screen devices, and imagers. Indium tin oxide (ITO), or other transparent conductive oxides, have been used, and provide a baseline sheet resistance (RS) vs. transparency (T) relationship. Several alternative material systems have been investigated. The development of high-performance hybrid structures provides a route towards robust, scalable and low-cost approaches for realizing high-performance TCE.

  17. Treasure of the Past VI: Standard Potential of the Silver-Silver-Chloride Electrode from 0° to 95° C and the Thermodynamic Properties of Dilute Hydrochloric Acid Solutions

    PubMed Central

    Bates, Roger G.; Bower, Vincent E.

    2001-01-01

    From electromotive-force measurements of the cell without liquid junction: Pt;H2,HCl(m),AgCl;Agthrough the range 0° to 95° C, calculations have been made of (1) the standard potential of the silver–silver-chloride electrode, (2) the activity coefficient of hydrochloric acid in aqueous solutions from m (molality) =0 to m=0.1 and from 0° to 90° C, (3) the relative partial molal heat content of hydrochloric acid, and (4) the relative partial molal heat capacity of hydrochloric acid. The extrapolations were made by the method of least squares with the aid of punch-card techniques. Data from at least 24 cells were analyzed at each temperature, and 81 cells were studied at 25° C. The value of the standard potential was found to be 0.22234 absolute volt at 25° C, and the standard deviation was 0.02 millivolt at 0° C, 0.01 millivolt at 25° C, and 0.09 millivolt at 95° C. The results from 0° to 60° C are compared with earlier determinations of the standard potential and other quantities derived from the electromotive force.

  18. Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells

    NASA Astrophysics Data System (ADS)

    José Andrés, Luis; Menéndez, María Fe; Gómez, David; Martínez, Ana Luisa; Bristow, Noel; Kettle, Jeffrey Paul; Menéndez, Armando; Ruiz, Bernardino

    2015-07-01

    Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

  19. Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells.

    PubMed

    José Andrés, Luis; Fe Menéndez, María; Gómez, David; Luisa Martínez, Ana; Bristow, Noel; Paul Kettle, Jeffrey; Menéndez, Armando; Ruiz, Bernardino

    2015-07-01

    Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed. PMID:26056864

  20. Electrochemical sensor using neomycin-imprinted film as recognition element based on chitosan-silver nanoparticles/graphene-multiwalled carbon nanotubes composites modified electrode.

    PubMed

    Lian, Wenjing; Liu, Su; Yu, Jinghua; Li, Jie; Cui, Min; Xu, Wei; Huang, Jiadong

    2013-06-15

    A novel imprinted electrochemical sensor for neomycin recognition was developed based on chitosan-silver nanoparticles (CS-SNP)/graphene-multiwalled carbon nanotubes (GR-MWCNTs) composites decorated gold electrode. Molecularly imprinted polymers (MIPs) were synthesized by electropolymerization using neomycin as the template, and pyrrole as the monomer. The mechanism of the fabrication process and a number of factors affecting the activity of the imprinted sensor have been discussed and optimized. The characterization of imprinted sensor has been carried out by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry (CV) and amperometry. Under the optimized conditions, the linear range of the sensor was from 9×10(-9)mol/L to 7×10(-6)mol/L, with the limit of detection (LOD) of 7.63×10(-9)mol/L (S/N=3). The film exhibited high binding affinity and selectivity towards the template neomycin, as well as good reproducibility and stability. Furthermore, the proposed sensor was applied to determine the neomycin in milk and honey samples based on its good reproducibility and stability, and the acceptable recovery implied its feasibility for practical application. PMID:23395725

  1. Silver nanoflower-reduced graphene oxide composite based micro-disk electrode for insulin detection in serum.

    PubMed

    Yagati, Ajay Kumar; Choi, Yonghyun; Park, Jinsoo; Choi, Jeong-Woo; Jun, Hee-Sook; Cho, Sungbo

    2016-06-15

    Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs). The morphology of AgNF-rGO composite was characterized by scanning electron microscopy, the structure was analyzed using X-ray diffraction patterns and Raman spectra. The hybrid interface exhibited enhanced electrical conductivity when compared with its individual elements and had improved capturing ability for antibody-antigen binding towards insulin detection. In order to measure quantitatively the insulin concentration in PBS and human serum, the change in impedance (ΔZ) from electrochemical impedance spectroscopy was analyzed for various concentrations of insulin in [Fe(CN)6](3-/4-) redox couple. The electrode with adsorbed antibodies showed an increase in ΔZ for the addition of antigen concentrations over a working range of 1-1000 ng mL(-1). The detection limits were 50 and 70 pg mL(-1) in PBS and human serum, respectively. PMID:26852199

  2. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter

    NASA Astrophysics Data System (ADS)

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Jhon, Young Min; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm2 V‑1 s‑1 for the p-channel and 0.027 cm2 V‑1 s‑1 for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area.

  3. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter.

    PubMed

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Min Jhon, Young; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm(2) V(-1) s(-1) for the p-channel and 0.027 cm(2) V(-1) s(-1) for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area. PMID:27114463

  4. Surface enhanced Raman spectroscopy of the silver/KCl, triethylenediamine (DABCO), water system

    NASA Astrophysics Data System (ADS)

    Irish, D. E.; Guzonas, D.; Atkinson, G. F.

    1985-07-01

    1,4-Diazabicyclo[2.2.2]octane, (N(CH 2CH 2) 3N), usually abbreviated DABCO or DBO, is a symmetric top molecule of point group D 3h. SERS experiments have been carried out in an optical electrochemical cell using a silver electrode roughened by a single oxidation-reduction cycle (ORC). The observed SERS spectra contained four strong bands at 624, 798, 990 and 1351 cm -1, all A' 1 totally symmetric modes. The same bands were also observed in SERS spectra of DABCO adsorbed on colloidal gold. In the electrochemical experiments, the maximum of SERS-intensity versus electrode potential plots was observed to shift to less negative potentials as the wavelength of the exciting line was shifted to the red. The radically-altered, relative intensities of the observed bands, as well as observed changes in relative intensity as a function of electrode potential, have been interpreted as a selective enhancement of those normal modes which have as a major component of vibrational motion the C-C stretch. These observations are correlated with current theories concerning the SERS mechanism, especially those involving charge transfer (CT).

  5. Amperometric Detection of Aqueous Silver Ions by Inhibition of Glucose Oxidase Immobilized on Nitrogen-Doped Carbon Nanotube Electrodes.

    PubMed

    Rust, Ian M; Goran, Jacob M; Stevenson, Keith J

    2015-07-21

    An amperometric glucose biosensor based on immobilization of glucose oxidase on nitrogen-doped carbon nanotubes (N-CNTs) was successfully developed for the determination of silver ions. Upon exposure to glucose, a steady-state enzymatic turnover rate was detected through amperometric oxidation of the H2O2 byproduct, directly related to the concentration of glucose in solution. Inhibition of the steady-state enzymatic glucose oxidase reaction by heavy metals ions such as Ag(+), produced a quantitative decrease in the steady-state rate, subsequently creating an ultrasensitive metal ion biosensor through enzymatic inhibition. The Ag(+) biosensor displayed a sensitivity of 2.00 × 10(8) ± 0.06 M(-1), a limit of detection (σ = 3) of 0.19 ± 0.04 ppb, a linear range of 20-200 nM, and sample recovery at 101 ± 2%, all acquired at a low-operating potential of 0.05 V (vs Hg/Hg2SO4). Interestingly, the biosensor does not display a loss in sensitivity with continued use due to the % inhibition based detection scheme: loss of enzyme (from continued use) does not influence the % inhibition, only the overall current associated with the activity loss. The heavy metals Cu(2+) and Co(2+) were also detected using the enzyme biosensor but found to be much less inhibitory, with sensitivities of 1.45 × 10(6) ± 0.05 M(-1) and 2.69 × 10(3) ± 0.07 M(-1), respectively. The mode of GOx inhibition was examined for both Ag(+) and Cu(2+) using Dixon and Cornish-Bowden plots, where a strong correlation was observed between the inhibition constants and the biosensor sensitivity. PMID:26079664

  6. Silver nanoparticle-decorated carbon nanotubes as bifunctional gas-diffusion electrodes for zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, T.; Kaempgen, M.; Nopphawan, P.; Wee, G.; Mhaisalkar, S.; Srinivasan, M.

    Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for mobile and portable applications.

  7. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.; Turchan, M.; Hopkins, J.

    1972-01-01

    Electrodes for a nongassing negative limited nickel-cadmium cell are discussed. The key element is the development of cadmium electrodes with high hydrogen overvoltage. For this, the following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver-sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures.

  8. Kinetic Roughening Transition and Energetics of Tetragonal Lysozyme Crystal Growth

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

    2004-01-01

    Interpretation of lysozyme crystal growth rates using well-established physical theories enabled the discovery of a phenomenon possibly indicative of kinetic roughening. For example, lysozyme crystals grown above a critical supersaturation sigma, (where supersaturation sigma = ln c/c(sub eq), c = the protein concentration and c(sub eq) = the solubility concentration) exhibit microscopically rough surfaces due to the continuous addition of growth units anywhere on the surface of a crystal. The rate of crystal growth, V(sub c), for the continuous growth process is determined by the continuous flux of macromolecules onto a unit area of the crystal surface, a, from a distance, xi, per unit time due to diffusion, and a probability of attachment onto the crystal surface, expressed. Based upon models applied, the energetics of lysozyme crystal growth was determined. The magnitudes of the energy barriers of crystal growth for both the (110) and (101) faces of tetragonal lysozyme crystals are compared. Finally, evidence supportive of the kinetic roughening hypothesis is presented.

  9. Stress induced roughening of superclimbing dislocation in solid 4He

    NASA Astrophysics Data System (ADS)

    Aleinikava, Darya; Kuklov, Anatoly

    2011-03-01

    We investigate numerically superclimb of dislocation in solid 4 He biased by externally imposed chemical potential μ . The effective action takes into account quantum phase slips in the core superfluid as well as the core displacement in Peierls potential within the Granato-Lücke string model. The bias produces stress on the core and this can result in dislocation roughening. Such roughening is characterized by hysteretic behavior at temperatures (T) below some threshold Thyst . At T >Thyst strongresonantpeaksdevelopinthedislocationdifferentialresponse . Thesepeaksexhibitperiodicbehaviorvs μ, with the period determined by Peierls potential and dislocation length. We explain these effects by thermally assisted tunneling of jog-antijog pairs across the barrier created by Peierls potential and the bias. Since superclimbing is controlled by core superflow, speed of sound along the superfluid core exhibits dip-like features at the peak positions. We propose that this effect is seen in the mass transport experiment. We acknowledge support by NSF, grants PHY1005527 and PHY0653135,and by CUNY, grant 63071-00 41.

  10. Local diffusion induced roughening in cobalt phthalocyanine thin film growth.

    PubMed

    Gedda, Murali; Subbarao, Nimmakayala V V; Goswami, Dipak K

    2014-07-29

    We have studied the kinetic roughening in the growth of cobalt phthalocyanine (CoPc) thin films grown on SiO2/Si(001) surfaces as a function of the deposition time and the growth temperature using atomic force microscopy (AFM). We have observed that the growth exhibits the formation of irregular islands, which grow laterally as well as vertically with coverage of CoPc molecules, resulting rough film formation. Our analysis further disclosed that such formation is due to an instability in the growth induced by local diffusion of the molecules following an anomalous scaling behavior. The instability relates the (ln(t))(1/2), with t as deposition time, dependence of the local surface slope as described in nonequilibrium film growth. The roughening has been characterized by calculating different scaling exponents α, β, and 1/z determined from the height fluctuations obtained from AFM images. We obtained an average roughness exponent α = 0.78 ± 0.04. The interface width (W) increases following a power law as W ∼ t(β), with growth exponent β = 0.37 ± 0.05 and lateral correlation length (ξ) grows as ξ ∼ t(1/z) with dynamic exponent 1/z = 0.23 ± 0.06. The exponents revealed that the growth belongs to a different class of universality. PMID:24992503

  11. Sputter roughening instability on the Ge(001) surface: Energy and flux dependence

    SciTech Connect

    Chason, E.; Mayer, T.M.; Kellerman, B.K.

    1995-12-31

    We have measured surface roughening kinetics during low energy Xe ion sputtering of Ge (001) surfaces. Results are interpreted in terms of an instability theory developed by Bradley and Harper. Although the calculated magnitude of the roughening rate does not agree with the measured value, the variation of the rate with ion flux and energy is on agreement with the theory.

  12. Smoothing and roughening of slip surfaces in direct shear experiments

    NASA Astrophysics Data System (ADS)

    Sagy, Amir; Badt, Nir; Hatzor, Yossef H.

    2015-04-01

    , increases as a function of slip amount. The roughness measured after slip can be fitted by a power-law similar to that of the initial tensile surface. In the next series of experiments a similar procedure is applied when the roughness evolution is measured as a function of increasing normal stress for a fixed displacement amount of 10 mm. While samples sheared under a constant normal stress of 5 MPa generated surface smoothing, shearing under normal stress of 7.5 MPa to 15 MPa exhibited surface roughening at the measured range of scales. We find that roughening is correlated with the attained peak shear stress values, stress drop (peak shear stress minus residual shear stress) and with wear accumulation, a novel measurement procedure of which is developed here. Analysis of the sheared samples shows that roughening is generated by sets of dense fractures that significantly damaged the sample in the immediate proximity to large asperities. This roughening is related to penetrative damage during transient wear in rough surfaces.

  13. Gelatin coated electrodes allow prolonged bioelectronic measurements

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Silver electrodes treated with an anodizing electrolyte containing gelatin are used for long term monitoring of bioelectronic potentials in humans. The electrodes do not interact with perspiration, cause skin irritation, or promote the growth of bacteria.

  14. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  15. Acoustic transmission across a roughened fluid-fluid interface.

    PubMed

    Lim, R; Paustian, I C; Lopes, J L

    2001-04-01

    A set of tank experiments was performed to investigate acoustic transmission across a roughened fluid-fluid interface with the intention to test heuristic Bragg scattering predictions used to explain observations of anomalous transmission in field experiments. In the tank experiments, two immiscible fluids (vegetable oil floating on glycerin) formed the layers. Small polystyrene beads were floated at the interface to simulate roughness. An array of hydrophones placed in the bottom layer (glycerin) was used to measure the acoustic levels transmitted across the interface. This array was also employed as a beamformer to determine the apparent angle and sound speed of the scattered signals. Data were acquired at subcritical grazing angles in the frequency range of 100-200 kHz for three different bead diameters and for various configurations in which the locations of the beads floating on the interface were varied. Results of these measurements demonstrated that a significant amount of acoustic energy can be scattered into the bottom layer by beads floating at the interface. The scattered levels increased with increasing bead diameter. However, discrepancies occurred between observed propagation properties and the Bragg predictions. By comparing the processed tank data to a computer simulation of the same it was determined that these discrepancies are a consequence of near-field reception of the scattering by the bead array and ignoring the directionality of the scattering by the beads. Consequences to observations made in field experiments are discussed. PMID:11325108

  16. Biomechanical and Histological Evaluation of Roughened Surface Titanium Screws Fabricated by Electron Beam Melting

    PubMed Central

    Yang, Jun; Cai, Hong; Lv, Jia; Zhang, Ke; Leng, Huijie; Wang, Zhiguo; Liu, Zhongjun

    2014-01-01

    Background Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Methods Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. Results No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Conclusions Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws. PMID:24788866

  17. Highly compliant transparent electrodes

    NASA Astrophysics Data System (ADS)

    Shian, Samuel; Diebold, Roger M.; McNamara, Alena; Clarke, David R.

    2012-08-01

    Adaptive optical devices based on electric field induced deformation of dielectric elastomers require transparent and highly compliant electrodes to conform to large shape changes. Electrical, optical, and actuation properties of acrylic elastomer electrodes fabricated with single-walled carbon nanotubes (SWCNTs) and silver nanowires (AgNWs) have been evaluated. Based on these properties, a figure of merit is introduced for evaluating the overall performance of deformable transparent electrodes. This clearly indicates that SWCNTs outperform AgNWs. Under optimal conditions, optical transparency as high as 91% at 190% maximum actuation strain is readily achievable using SWCNT electrodes.

  18. Rugged pressed disk electrode has low contact potential

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Mosier, B.

    1965-01-01

    Pressed-disk electrode with low contact potential monitors physiological processes. It consists of silver and silver chloride combined with bentonitic clay. The clay affords a surface that permits use over extended periods without contact deterioration.

  19. Glass frits coated with silver nanoparticles for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  20. Solid-solid phase transformation: Roughening of stylolites

    NASA Astrophysics Data System (ADS)

    Angheluta, L.; Jettestuen, E.; Mathiesen, J.; Renard, F.; Jamtveit, B.

    2007-12-01

    Sedimentary rocks under uniaxial compression often react by changing the texture during compaction or cementation, which is accompanied by the formation of stylolites spanning the grain contacts or the rocks along surfaces normal to the applied stress. Many field observations corroborate a common feature of stylolites, namely that they are rough interfaces that contain insoluble minerals. Stylolites are outstanding examples of interfacial patterns developed in out-of-equilibrium systems. We study the roughening of stylolites within a model of a moving interface boundary between two stressed solids. The set up of our model consists of two dissimilar elastic bodies that are separated by a sharp interface and subjected to uniform compression in the direction perpendicular to the interface profile. Based on the balance laws of force and energy, we derive the jump conditions for a moving interface driven by a phase transformation process, i.e. the solid phase with higher energy (more porous) is removed and replaced by the same amount of less porous solid phase. An initially flat interface perturbed with small irregularities develops grooves or finger like structures, which align with the principal direction of compaction. The system is dissipative and approaches asymptotically the equilibrium configuration between the two phases. Our numerical investigations reveal several issues: 1) a morphological instability of the solid-solid interface does develop; 2) the instability is driven by the porosity jump across the interface; 3) the energy concentration at the tip of the fingers may influence the development of cracks perpendicular to the stylolites planes, as observed in nature.

  1. Soft-Etching Copper and Silver Electrodes for Significant Device Performance Improvement toward Facile, Cost-Effective, Bottom-Contacted, Organic Field-Effect Transistors.

    PubMed

    Wang, Zongrui; Dong, Huanli; Zou, Ye; Zhao, Qiang; Tan, Jiahui; Liu, Jie; Lu, Xiuqiang; Xiao, Jinchong; Zhang, Qichun; Hu, Wenping

    2016-03-01

    Poor charge injection and transport at the electrode/semiconductor contacts has been so far a severe performance hurdle for bottom-contact bottom-gate (BCBG) organic field-effect transistors (OFETs). Here, we have developed a simple, economic, and effective method to improve the carrier injection efficiency and obtained high-performance devices with low cost and widely used source/drain (S/D) electrodes (Ag/Cu). Through the simple electrode etching process, the work function of the electrodes is more aligned with the semiconductors, which reduces the energy barrier and facilitates the charge injection. Besides, the formation of the thinned electrode edge with desirable micro/nanostructures not only leads to the enlarged contact side area beneficial for the carrier injection but also is in favor of the molecular self-organization for continuous crystal growth at the contact/active channel interface, which is better for the charge injection and transport. These effects give rise to the great reduction of contact resistance and the amazing improvement of the low-cost bottom-contact configuration OFETs performance. PMID:26967358

  2. Powder processing of hybrid titanium neural electrodes

    NASA Astrophysics Data System (ADS)

    Lopez, Jose Luis, Jr.

    A preliminary investigation into the powder production of a novel hybrid titanium neural electrode for EEG is presented. The rheological behavior of titanium powder suspensions using sodium alginate as a dispersant are examined for optimal slip casting conditions. Electrodes were slip cast and sintered at 950°C for 1 hr, 1000°C for 1, 3, and 6 hrs, and 1050°C for 1 hr. Residual porosities from sintering are characterized using Archimedes' technique and image analysis. The pore network is gel impregnated by submerging the electrodes in electrically conductive gel and placing them in a chamber under vacuum. Gel evaporation of the impregnated electrodes is examined. Electrodes are characterized in the dry and gelled states using impedance spectrometry and compared to a standard silver- silver chloride electrode. Power spectral densities for the sensors in the dry and gelled state are also compared. Residual porosities for the sintered specimens were between 50.59% and 44.81%. Gel evaporation tests show most of the impregnated gel evaporating within 20 min of exposure to atmospheric conditions with prolonged evaporation times for electrodes with higher impregnated gel mass. Impedance measurements of the produced electrodes indicate the low impedance of the hybrid electrodes are due to the increased contact area of the porous electrode. Power spectral densities of the titanium electrode behave similar to a standard silver-silver chloride electrode. Tests suggest the powder processed hybrid titanium electrode's performance is better than current dry contact electrodes and comparable to standard gelled silver-silver chloride electrodes.

  3. Deposition characteristics of copper particles on roughened substrates through kinetic spraying

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Bae, Gyuyeol; Lee, Changhee

    2009-01-01

    In this paper, a systematic study of copper particle deposition behavior on polished and roughened surfaces (aluminum and copper) in kinetic spray process has been performed. The particle deformation behavior was simulated through finite element analysis (FEA) software ABAQUS explicit 6.7-2. The particle-substrate contact time, contact temperature and contact area upon impact have been estimated for smooth and three different roughened substrate cases. Copper powders were deposited on smooth and grit-blasted copper and aluminium substrates and characterized through scanning electron microscopy and Romulus bond strength analyzer. The results indicate that the deformation and the resultant bonding were higher for the roughened substrates than that of smooth. The characteristic factors for bonding are reported and discussed. Thus the substrate roughness appears to be beneficial for the initial deposition efficiency of the kinetic spray process.

  4. Roughening and removal of surface contamination from beryllium using negative transferred-arc cleaning

    SciTech Connect

    Castro, R.G.; Hollis, K.J.; Elliott, K.E.

    1997-12-01

    Negative transferred-arc (TA) cleaning has been used extensively in the aerospace industry to clean and prepare surfaces prior to plasma spraying of thermal barrier coatings. This non-line of sight process can improve the bond strength of plasma sprayed coatings to the substrate material by cleaning and macroscopically roughening the surface. A variation of this cleaning methodology is also used in gas tungsten arc (GTA) welding to cathodically clean the surfaces of aluminum and magnesium prior to welding. Investigations are currently being performed to quantify the degree in which the negative transferred-arc process can clean and roughen metal surfaces. Preliminary information will be reported on the influence of processing conditions on roughening and the removal of carbon and other contaminates from the surface of beryllium. Optical, spectral and electrical methods to quantify cleaning of the surface will also be discussed. Applications for this technology include chemical-free precision cleaning of beryllium components.

  5. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum.

    PubMed

    Lata, Kusum; Dhull, Vikas; Hooda, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM-5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  6. In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

    NASA Astrophysics Data System (ADS)

    Li, Dan; Jia, Shaojie; Fodjo, Essy Kouadio; Xu, Hu; Wang, Yuhong; Deng, Wei

    2016-03-01

    In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from -0.3 to -0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from -0.3 to -0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

  7. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum

    PubMed Central

    Lata, Kusum; Dhull, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM–5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  8. Large silver-cadmium technology program

    NASA Technical Reports Server (NTRS)

    Charlip, S.; Lerner, S.

    1971-01-01

    The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

  9. Electrode for a lithium cell

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2008-10-14

    This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV.sub.3O.sub.8 as one component and one or more other components consisting of LiV.sub.3O.sub.8, Ag.sub.2V.sub.4O.sub.11, MnO.sub.2, CF.sub.x, AgF or Ag.sub.2O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

  10. Roughening and reflection performance of molybdenum coatings exposed to a high-flux deuterium plasma

    NASA Astrophysics Data System (ADS)

    Eren, B.; Marot, L.; Ryzhkov, I. V.; Lindig, S.; Houben, A.; Wisse, M.; Skoryk, O. O.; Oberkofler, M.; Voitsenya, V. S.; Linsmeier, Ch.; Meyer, E.

    2013-11-01

    Optical diagnostic systems of ITER are foreseen to include metallic, plasma-facing, electromagnetic radiation reflecting components called first mirrors (FMs). Molybdenum coatings are important candidates for these components. Depending on the local plasma parameters of the reactor, the mirrors may be under net erosion or deposition conditions. In this work, we exposed molybdenum coatings to a high-flux deuterium plasma in order to test their roughening limits under erosion conditions. The high energy of deuterium ions (500 eV on average) results in more vigorous roughening of the surface compared with lower energy ions (200 eV). Longer exposure (3 × 1020 ions cm-2) of the 200 eV ions results in only a slightly increased roughness compared with shorter exposure (6.8 × 1019 ions cm-2). Both phenomena match to the theory regarding roughening dynamics of physical sputtering. A comparison of results in this work with previous studies gives support to the hypothesis that roughening is flux and temperature dependent. Partial delamination of the coatings is observed upon exposure at room temperature, but not at an elevated temperature (200 °C). In summary, Mo coatings will remain functional in the ITER environment under the expected conditions. However, changes in the expected conditions such as 500 eV mean energy of impinging charge exchange neutrals or <100 °C surface temperature of the mirrors can lead to gradual or sudden failure of the coatings.

  11. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.

    1971-01-01

    A research program to develop and evaluate electrodes for a nongassing negative limited nickel-cadmium cell is described. The concept of the negative limited cell and its implications on electrode structure are discussed. The key element is the development of a cadmium electrode with high hydrogen overvoltage. For this, Teflon-bonded Cd electrodes and silver-sinter based Gc electrodes were manufactured and in preliminary experiments their physical and electrochemical characteristics were evaluated. Hydrogen evolution on cadmium was found to occur approximately 100 mV more cathodic than on silver. Both electrode structures exhibit a fairly sharp potential rise at the end of the charging cycle and the advent of gas evolution occurs at potentials between -1.2 and -1.3 V versus a Hg/HgO reference electrode. These results are compared with conventional Ni-sinter based Cd electrodes.

  12. Roughening transition in nanoporous hydrogenated amorphous germanium: Roughness correlation to film stress

    NASA Astrophysics Data System (ADS)

    Carroll, M. S.; Verley, J. C.; Sheng, J. J.; Banks, J.

    2007-03-01

    Hydrogenated amorphous germanium (a-Ge:H) is a material of interest for optoelectronic applications such as solar cells and radiation detectors because of the material's potential to extend the wavelength sensitivity of hydrogenated amorphous silicon (a-Si:H). An increase in porosity is observed in amorphous germanium compared to a-Si :H, and this increase in porosity has been correlated with a degradation of the electrical performance. Improved understanding of the mechanisms of porous formation in a-Ge :H films is therefore desirable in order to better control it. In this paper we describe a correlation between film stress and surface roughness, which evolves with increasing thickness of a-Ge :H. A roughening transition from planar two-dimensional growth to three-dimensional growth at a critical thickness less than 800Å results in a network of needlelike nanotrench cavities which stretch from the transition thickness to the surface in films up to 4000Å thick. Surface roughness measurements by atomic force microscope and transmission electron microscopy indicate that the transition is abrupt and that the roughness increases linearly after the transition thickness. The roughening transition thickness is, furthermore, found to correlate with the maxima of the integrated compressive stress. The compressive stress is reduced after this transition thickness due to the incorporation of nanovoids into the film that introduce tensile stress as the islands coalesce together. The roughening transition behavior is similar to that found in a general class of Volmer-Weber mode thin film deposition (e.g., Cu, Ag, and nonhydrogenated amorphous silicon), which offers additional insight into the underlying mechanisms of the stress and roughening in these a-Ge :H films. The suppression of the roughening transition by changing the kinetics of the deposition rates (e.g., slowing the deposition rate with a weak sputtering bias) is also observed and discussed.

  13. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    NASA Astrophysics Data System (ADS)

    Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-01

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl2 plasmas, as a function of rf bias power or ion incident energy Ei, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on Ei: one is the roughening mode at low Ei < 200-300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing Ei, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher Ei, where the rms surface roughness decreases substantially with Ei down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on Ei were also observed in the etch rate versus √{Ei } curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing Ei were found to correspond to changes in the predominant ion flux from feed gas ions Clx+ to ionized etch products SiClx+ caused by the increased etch rates at increased Ei, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  14. Determination of Silver(I) by Differential Pulse Voltammetry Using a Glassy Carbon Electrode Modified with Synthesized N-(2-Aminoethyl)-4,4′-Bipyridine

    PubMed Central

    Radulescu, Maria-Cristina; Chira, Ana; Radulescu, Medeea; Bucur, Bogdan; Bucur, Madalina Petruta; Radu, Gabriel Lucian

    2010-01-01

    A new modified glassy carbon electrode (GCE) based on a synthesized N-(2-aminoethyl)-4,4′-bipyridine (ABP) was developed for the determination of Ag(I) by differential pulse voltammetry (DPV). ABP was covalently immobilized on GC electrodes surface using 4-nitrobenzendiazonium (4-NBD) and glutaraldehyde (GA). The Ag(I) ions were preconcentrated by chemical interaction with bipyridine under a negative potential (−0.6 V); then the reduced ions were oxidized by differential pulse voltammetry and a peak was observed at 0.34 V. The calibration curve was linear in the concentration range from 0.05 μM to 1 μM Ag(I) with a detection limit of 0.025 μM and RSD = 3.6%, for 0.4 μM Ag(I). The presence of several common ions in more than 125-fold excess had no effect on the determination of Ag(I). The developed sensor was applied to the determination of Ag(I) in water samples using a standard addition method. PMID:22163530

  15. A view of aqueous electrochemical carbon dioxide reduction to formate at indium electrodes, and the reversible electrodeposition of silver in ionic liquids through the lens of fundamental surface science

    NASA Astrophysics Data System (ADS)

    Detweiler, Zachary M.

    Two systems were studied using in situ measurement techniques, demonstrating the importance of creative experimental design. The electroreduction of CO2 at heterogeneous indium electrodes in aqueous solution was analyzed by cyclic voltammetry. Bulk electrolyses showed that increased indium oxide presence prior to electrolysis improved the Faradaic efficiency of CO 2 reduction to formate in 0.5 M K2SO2 aqueous solutions at a pH of 4.4. In order to more accurately assign speciation at the electrode surface ex situ O2 and H2O dosing of metallic indium under UHV was studied with XPS, HREELS and TPD. Ambient pressure XPS showed that the ratio of oxide to hydroxide at the indium interface is strongly dependent on the partial pressure of water; decreasing as P(H2O) increases. Using this information, a qualitative picture of the indium interface could be generated. In situ ATR-FTIR with an indium thin film as the working electrode showed that bulk oxide quickly reduces with applied potential, but an interfacial oxide is still present at high reductive overpotential. Additionally, an adsorbed carbonate at the thin film interface was observed upon introducing CO 2 to the cell. The implication of a surface bound carbonate as the CO 2 reduction intermediate draws on a mechanism that has not previously been discussed in the electrochemical reduction of CO2. The previous study of this mechanism from Ficscher-Tropsch literature helps to predict the further reduced products found at more electropositive metals, such as copper or magnesium, the latter of which is described here. Additionaly described here is a series of ILs that were employed as electrolyte for reversible silver deposition. BMIM N(TfO)2 was found to be the most promising of those studied, intrinsically giving a more uniform deposit that was bright and reversible. Deposit formation was studied using SEM and EDX as a function of deposition potential and deposition time. In situ reflectometry was employed to get a

  16. Improved conductive paste secures biomedical electrodes

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Nontoxic paste consisting of a dispersion of graphite or silver granules in a mixture of polyvinylpyrolidone and diluted glycerol secures biomedical electrodes to human skin. Silver paste has a high electrical conductivity and forms a bond between metal and moist or dry skin.

  17. Vibrational Sum Frequency Study of the Influence of Water-Ionic Liquid Mixtures in the CO2 Electroreduction on Silver Electrodes

    NASA Astrophysics Data System (ADS)

    Garcia Rey, Natalia; Dlott, Dana

    2015-06-01

    Understand the molecular dynamics on buried electrodes under electrochemical transformations is of significant interest. There is a big gap of knowledge in the CO2 electroreduction mechanism due to the limitations to access and probe the liquid-metal interfaces [1,2]. Vibrational Sum Frequency Spectroscopy (VSFS) is a non-invasive and surface sensitive technique, with molecular level detection that can be used to probe electrochemical reactions occurring on the electrolyte-electrode interface [2]. We observed the CO2 electroreduction to CO in ionic liquids (ILs) on poly Ag using VSFS synchronized with cyclic voltammetry. In order to follow the CO2 reaction in situ on the ionic liquid-Ag interface; the CO, CO2 and imidazolium vibrational modes (resonant SFS) were monitored as a function of potential. We identified at which potential the CO was produced and how the EMIM-BF4 played an important role in the electron transfer to the CO2, lowering the CO2- energy barrier. A new approach to reveal the double layer dynamics to the electrostatic environment is presented by the study of the nonresonant sum frequency intensity as a function of the applied potential. By this method, we studied the influence of water-ionic liquid mixtures in the CO2 electroreduction on Ag electrode. We observed a shift to lower potentials in the CO2 electroreduction in water-ILs electrolyte. Previous studies in gas diffusion fuel cells have shown the CO2 electroreduction in a water-imidazolium-based ILs on Ag nanoparticles at lower overpotential [3]. Our VSFS study helps to understand the fundamental electrochemical mechanism, showing how the ILs structural transition influences the CO2 electroreduction. [1] Polyansky, D. E.; Electroreduction of Carbon Dioxide, 2014, Encyclopedia of Applied Electrochemistry, Springer New York, pag 431-437. [2] Bain, C. D.; J. Chem. Soc., Faraday Trans., 1995, 91, 1281. [3] Rosen, B. A. et al; Science, 2011, 334 (6056), 643. Rosen, B. A. et al.; J. electrochem

  18. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  19. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  20. Low-temperature sintering and compatibility with silver electrode of Ba{sub 4}MgTi{sub 11}O{sub 27} microwave dielectric ceramic

    SciTech Connect

    Chen, Xiuli; Zhou, Huanfu; Fang, Liang; Liu, Laijun; Li, Changda; Guo, Ruli; Wang, Hong

    2010-10-15

    Ba{sub 4}MgTi{sub 11}O{sub 27} microwave dielectric ceramic was investigated using X-ray diffraction, scanning electron microscopy and dielectric measurement. The pure Ba{sub 4}MgTi{sub 11}O{sub 27} ceramic shows a high sintering temperature ({approx}1275 {sup o}C) and good microwave dielectric properties as Q x f of 19,630 GHz, {epsilon}{sub r} of 36.1, {tau}{sub f} of 14.6 ppm/{sup o}C. It was found that the addition of BaCu(B{sub 2}O{sub 5}) (BCB) can effectively lower the sintering temperature from 1275 to 925 {sup o}C, and does not induce much degradation of the microwave dielectric properties. The BCB-doped Ba{sub 4}MgTi{sub 11}O{sub 27} ceramics can be compatible with Ag electrode, which makes it a promising ceramic for LTCC technology application.

  1. Improved bipolar resistive switching memory characteristics in Ge0.5Se0.5 solid electrolyte by using dispersed silver nanocrystals on bottom electrode.

    PubMed

    Kim, Jang-Han; Nam, Ki-Hyun; Hwang, Inchan; Cho, Won-Ju; Park, Byoungchoo; Chung, Hong-Bay

    2014-12-01

    Resistive switching random-access memory (ReRAM) devices based on chalcogenide solid electrolytes have recently become a promising candidate for future low-power nanoscale nonvolatile memory application. The resistive switching mechanism of ReRAM is based on the formation and rupture of conductive filament (CF) in the chalcogenide solid electrolyte layers. However, the random diffusion of metal ions makes it hard to control the CF formation, which is one of the major obstacles to improving device performance of ReRAM devices. We demonstrate the spin-coated metal nanocrystals (NCs) enhance the bipolar resistive switching (BRS) memory characteristics. Compared to the Ag/Ge0.5Se0.5/Pt structure, excellent resistive switching memory characteristics were obtained from the Ag/Ge0.5Se0.5/Ag NCs/Pt structure. Ag NCs improve the uniformity of resistance values and reduce the reset voltage and current. A stable DC endurance (> 100 cycles) and a high data retention (> 10(4) sec) were achieved by spin coating the Ag NCs on the Pt bottom electrode for ReRAMs. PMID:25971090

  2. Optical characteristics of a wind-roughened water surface: a two-dimensional theory.

    PubMed

    Yoshimori, K; Itoh, K; Ichioka, Y

    1995-09-20

    We present a two-dimensional theory of thermal emission and light scattering from an anisotropic wind-roughened water surface that is described by the Gaussian-Joint North Sea Wave Project model. The theory is developed through the use of the first-order geometrical-optics approxmation modified with shadowing effects, and it is valid when the average slopes of the surface are smaller than unity. The theory allows us to evaluate the effective emissivity and the effective bistatic reflectivity of a full-gravity-capillary wave surface at large viewing angles, for any direction relative to the average propagation direction of the surface wave. We also present an application of the theory to the recently proposed method for obtaining thermal imagery of a wind-roughened water surface from low altitudes, which is called statistically corrected ocean thermography. Corrected thermal images of the ocean surface, obtained by our field experiment, are shown. PMID:21060466

  3. Atomic diffusion on vicinal surfaces: step roughening impact on step permeability

    NASA Astrophysics Data System (ADS)

    Ranguelov, B.; Michailov, M.

    2014-12-01

    The problem of mass transport in material science for systems with reduced dimensionality holds special academic and technological attention since the fine diffusion control of adatoms could initiate exotic nanoscale patterning at epitaxial interfaces. The present study brings out important details of the atomic diffusion mechanisms on vicinal surfaces, accounting for the subtle competition between an external field imposed on the migrating adatoms and the roughening of the steps bordering the atomic terraces. The computational model reveals a temperature gap for breakdown of step permeability in the vicinity of the step roughening transition and sheds light on recently observed experimental results for atomic step dynamics on Si surfaces. The present study also demonstrates the extended capability of atomistic models in computer simulations to unravel simultaneous effects, to distinguish between them, and finally to assess their specific contribution to experimentally observed complex physical phenomena.

  4. Intrinsic anomalous surface roughening of TiN films deposited by reactive sputtering

    SciTech Connect

    Auger, M. A.; Vazquez, L.; Sanchez, O.; Cuerno, R.; Castro, M.; Jergel, M.

    2006-01-15

    We study surface kinetic roughening of TiN films grown on Si(100) substrates by dc reactive sputtering. The surface morphology of films deposited for different growth times under the same experimental conditions were analyzed by atomic force microscopy. The TiN films exhibit intrinsic anomalous scaling and multiscaling. The film kinetic roughening is characterized by a set of local exponent values {alpha}{sub loc}=1.0 and {beta}{sub loc}=0.39, and global exponent values {alpha}=1.7 and {beta}=0.67, with a coarsening exponent of 1/z=0.39. These properties are correlated to the local height-difference distribution function obeying power-law statistics. We associate this intrinsic anomalous scaling with the instability due to nonlocal shadowing effects that take place during thin-film growth by sputtering.

  5. Spin-dependent effects in the roughened string model for heavy quarkonia

    SciTech Connect

    Kaur, R. ); Bambah, B.A. )

    1993-06-01

    Using the recently proposed roughened string potential for heavy quarkonium, we calculate the spin splitting in the [ital J]/[psi] and [Upsilon] systems. We show how the departure from linearity of this potential affects the hyperfine splitting in the [ital P] levels of these systems, in a way consistent with experimental data. This lends support to the recent observations that the confining part of the interquark potential is weaker than linear.

  6. Hypersonic heat-transfer and transition correlations for a roughened shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Bertin, J. J.; Stalmach, D. D.; Idar, E. S., III; Conley, D. B.; Goodrich, W. D.

    1976-01-01

    The effect of roughness on the heat transfer distributions and the transition criteria for the windward pitch plane of the shuttle orbiter at an angle of attack of 30 deg was studied using data obtained in hypersonic wind tunnels. The heat transfer distributions and the transition locations for the roughened models were compared with the corresponding data for smooth models. The data were correlated using theoretical solutions for a nonsimilar, laminar boundary layer subject to two different flow field models for the orbiter.

  7. Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

    NASA Technical Reports Server (NTRS)

    Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

    2013-01-01

    Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

  8. Higher-efficiency photoelectrochemical electrodes of titanium dioxide-based nanoarrays sensitized simultaneously with plasmonic silver nanoparticles and multiple metal sulfides photosensitizers

    NASA Astrophysics Data System (ADS)

    Guo, Keying; Liu, Zhifeng; Han, Jianhua; Zhang, Xueqi; Li, Yajun; Hong, Tiantian; Zhou, Cailou

    2015-07-01

    This paper describes a novel design of high-efficiency photoelectrochemical water splitting electrode, i.e., ordered TiO2 nanorod arrays (NRs) sensitized simultaneously with noble metal (Ag), binary metal sulfides (Ag2S) and ternary metal sulfides (Ag3CuS2) multiple photosensitizers for the first time. The TiO2/Ag/Ag2S/Ag3CuS2 NRs heterostructure is successfully synthesized through successive ion layer adsorption and reaction (SILAR) and a simple ion-exchange process based on ionic reaction mechanism. On the basis of an optimal quantity of Ag, Ag2S and Ag3CuS2 nanoparticles, such TiO2/Ag/Ag2S/Ag3CuS2 NRs exhibit a higher photoelectrochemical activity ever reported for TiO2-based nanoarrays in PEC water splitting, the photocurrent density is up to 9.82 mA cm-2 at 0.47 V versus Ag/AgCl, respectively. This novel architecture is able to increase electron collection efficiency and suppress carrier recombination via (i) a higher efficiency of light-harvesting through these multiple photosensitizers (Ag, Ag2S and Ag3CuS2); (ii) the efficient separation of photo-induced electrons and holes due to the direct electrical pathways; (iii) the surface plasmon resonance (SPR) effect of Ag nanoparticles, which enhances the efficient charge separation and high carrier mobility. This work is useful to explore feasible routes to further enhance the performance of oxide semiconductors for PEC water splitting to produce clean H2 energy.

  9. Directional grain growth from anisotropic kinetic roughening of grain boundaries in sheared colloidal crystals

    PubMed Central

    Gokhale, Shreyas; Nagamanasa, K. Hima; Santhosh, V.; Sood, A. K.; Ganapathy, Rajesh

    2012-01-01

    The fabrication of functional materials via grain growth engineering implicitly relies on altering the mobilities of grain boundaries (GBs) by applying external fields. Although computer simulations have alluded to kinetic roughening as a potential mechanism for modifying GB mobilities, its implications for grain growth have remained largely unexplored owing to difficulties in bridging the widely separated length and time scales. Here, by imaging GB particle dynamics as well as grain network evolution under shear, we present direct evidence for kinetic roughening of GBs and unravel its connection to grain growth in driven colloidal polycrystals. The capillary fluctuation method allows us to quantitatively extract shear-dependent effective mobilities. Remarkably, our experiments reveal that for sufficiently large strains, GBs with normals parallel to shear undergo preferential kinetic roughening, resulting in anisotropic enhancement of effective mobilities and hence directional grain growth. Single-particle level analysis shows that the mobility anisotropy emerges from strain-induced directional enhancement of activated particle hops normal to the GB plane. We expect our results to influence materials fabrication strategies for atomic and block copolymeric polycrystals as well. PMID:23169661

  10. Effect of abrasive surface roughening on the secondary yield of various metals

    NASA Astrophysics Data System (ADS)

    Graves, Timothy

    2007-11-01

    The secondary electron yield of metallic conductors plays a critical role in the development of multipactor discharges. These discharges require a secondary yield greater than unity at the appropriate energy level for sustained breakdown. By reducing the secondary yield below unity in the necessary energy range, multipactor and multipactor-induced glow discharges can be eliminated. Surface roughening has been shown to successfully lower the secondary yield to below unity (ref. 1). In addition, abrasive bead blasting has been shown to effectively reduce the secondary yield of copper surfaces while preserving voltage breakdown characteristics (ref. 2). This study investigates the effect of abrasive surface roughening on the secondary yield of materials such as copper, aluminum, and stainless steel. In addition to measuring the change in the secondary yield as a function of abrasive particle size, the multipactor resistance and voltage breakdown characteristics are investigated. In addition, the effect of vacuum conditioning via multipactor and rf plasma cleaning on the roughened surfaces will be discussed. Ref. 1. H. Bruining. Physics and Applications of Secondary Electron Emission. McGraw-Hill, NY, 1954. Ref. 2. T. P. Graves, Ph.D. Thesis, MIT. 2007

  11. Roughening in electronic growth of Ag on Si(111)-(7×7) surfaces.

    PubMed

    Pal, Arindam; Mahato, J C; Dev, B N; Goswami, D K

    2013-10-01

    Roughening in the electronic growth of Ag films on Si(111)-(7×7) surfaces for a film thickness ranging from 1 to 30 monolayers is reported. Ag films exhibit the growth of flat-top plateaus of preferential heights due quantum electronic effect. We have observed roughening of the film growth due to instability with linear diffusion characterized by the ln(θ)(1/2) dependence of the local surface slope, where θ is the Ag coverage. The roughening of the surface morphology has been characterized by scaling exponents α, β and 1/z, which are determined using scanning tunneling microscopy. Increased value of α = 0.67 ± 0.04 at the early stage of the electronic growth with two atomic layer height flat-top isolated Ag mounds to 0.77 ± 0.06 at the later stage of the growth when isolated mounds coalesce and form percolated structures maintaining preferential heights of an even number of atomic layers in the Ag mounds indicates the instability in the electronic growth. As a result, interface width W increases as a power law of coverage (θ), W ∼ θ(β), with growth exponent β = 0.33 ± 0.03, and lateral correlation length ξ grows as ξ ∼ θ(1/z) with 1/z = 0.27 ± 0.05. PMID:24015893

  12. Hierarchically roughened microplatelets enhance the strength and ductility of nacre-inspired composites.

    PubMed

    Niebel, Tobias P; Carnelli, Davide; Binelli, Marco R; Libanori, Rafael; Studart, André R

    2016-07-01

    Rough interfaces featuring nanoscale asperities are known to play a major role in the mechanics of nacre. Transferring this concept to artificial bioinspired composites requires a detailed understanding about the effect of the surface topography of reinforcing elements on the mechanical performance of such materials. To gain further insights into the effect of asperity size, hierarchy and coverage on the mechanics of nacre-inspired composites, we decorate alumina microplatelets with silica nanoparticles of selected sizes and use the resulting roughened platelets as reinforcing elements (15vol%) in a commercial epoxy matrix. For a single layer of silica nanoparticles on the platelet surface, increased ultimate strain and toughness are obtained with a large roughening particle size of 250nm. On the contrary, strength and stiffness are enhanced by decreasing the size of asperities using 22nm silica particles. By combining particles of two different sizes (100nm and 22nm) in a hierarchical fashion, we are able to improve stiffness and strength of platelet-reinforced polymers while maintaining high ultimate strain and toughness. Our results indicate that carefully designed hierarchically roughened interfaces lead to a more homogeneous stress distribution within the polymer matrix between the stiff reinforcing elements. By enabling the deformation of a larger fraction of the polymer matrix, this design concept improves the mechanical response of bioinspired composites and can possibly also be exploited to enhance the performance of conventional fiber-reinforced polymers. PMID:26926989

  13. HRLEED study of the roughening transitions in Cu(110), Ni(110) and Ag(110) surfaces

    SciTech Connect

    Wang, K.; Montano, P.A. |

    1996-12-01

    The authors present the results of High Resolution Low Energy Electron Diffraction (HRLEED) measurements of the thermal roughening transition on Cu(110), Ag(110) and Ni(110) surfaces. They performed careful spot profile intensity measurements as a function of temperature. They observed a proliferation of steps along the (110) and (001) directions. In addition a strong deviation from a Debye model was observed in the scattered intensity of the Bragg reflections. This deviation from the harmonic approximation occurs well below the roughening transition temperature. The behavior of the three metal surfaces is qualitatively similar except for the transition temperatures. Ni shows the highest transition temperature (1,300 K), Cu is intermediate (1,000 K) and Ag has the lowest temperature (730 K). Analyzing the behavior of the (00) reflection intensity, and the evolution of the line shape as a function of the temperature, they found clear evidence of a roughening transition at the (110) surface. A lineshape analysis of the (00) reflection shows the transition from a Lorentzian lineshape to a power law. They also proved, based on the experimental data and a recent theoretical model, that there is a tremendous increase in step density and a decrease in the average terrace size as the temperature increases. They used STM to corroborate the HRLEED results at room temperature. They found excellent agreement.

  14. Self-organized criticality in proteins: Hydropathic roughening profiles of G-protein-coupled receptors

    NASA Astrophysics Data System (ADS)

    Phillips, J. C.

    2013-03-01

    Proteins appear to be the most dramatic natural example of self-organized criticality (SOC), a concept that explains many otherwise apparently unlikely phenomena. Protein conformational functionality is often dominated by long-range hydrophobic or hydrophilic interactions which both drive protein compaction and mediate protein-protein interactions. Superfamily transmembrane G-protein-coupled receptors (GPCRs) are the largest family of proteins in the human genome; their amino acid sequences form the largest database for protein-membrane interactions. While there are now structural data on the heptad transmembrane structures of representatives of several heptad families, here we show how fresh insights into global and some local chemical trends in GPCR properties can be obtained accurately from sequences alone, especially by algebraically separating the extracellular and cytoplasmic loops from transmembrane segments. The global mediation of long-range water-protein interactions occurs in conjunction with modulation of these interactions by roughened interfaces. Hydropathic roughening profiles are defined here solely in terms of amino acid sequences, and knowledge of protein coordinates is not required. Roughening profiles both for GPCR and some simpler protein families display accurate and transparent connections to protein functionality, and identify natural length scales for protein functionality.

  15. Hybrid RANS/LES of turbulent flow in a rotating rib-roughened channel

    NASA Astrophysics Data System (ADS)

    Xun, Qian-Qiu; Wang, Bing-Chen

    2016-07-01

    In this paper, we investigate the effect of the Coriolis force on the flow field in a rib-roughened channel subjected to either clockwise or counter-clockwise system rotation using hybrid RANS/LES based on wall modelling. A simplified dynamic forcing scheme incorporating backscatter is proposed for the hybrid simulation approach. The flow is characterized by a Reynolds number of Re = 1.5 × 104 and a rotation number Ro ranging from -0.6 to 0.6. The mean flow speed and turbulence level near the roughened wall are enhanced under counter-clockwise rotation and suppressed under clockwise rotation. The Coriolis force significantly influences the stability of the wall shear layer and the free shear layers generated by the ribs. Consequently, it is interesting to observe that the classification of the roughness type relies not only on the pitch ratio, but also on the rotation number in the context of rotating rib-roughened flows. In order to validate the present hybrid approach, the first- and second-order statistical moments of the velocity field obtained from the simulations are thoroughly compared with the available laboratory measurement data.

  16. Molecular-Orientation-Induced Rapid Roughening and Morphology Transition in Organic Semiconductor Thin-Film Growth

    PubMed Central

    Yang, Junliang; Yim, Sanggyu; Jones, Tim S.

    2015-01-01

    We study the roughening process and morphology transition of organic semiconductor thin film induced by molecular orientation in the model of molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) using both experiment and simulation. The growth behaviour of F16CuPc thin film with the thickness, D, on SiO2 substrate takes on two processes divided by a critical thickness: (1) D ≤ 40 nm, F16CuPc thin films are composed of uniform caterpillar-like crystals. The kinetic roughening is confirmed during this growth, which is successfully analyzed by Kardar-Parisi-Zhang (KPZ) model with scaling exponents α = 0.71 ± 0.12, β = 0.36 ± 0.03, and 1/z = 0.39 ± 0.12; (2) D > 40 nm, nanobelt crystals are formed gradually on the caterpillar-like crystal surface and the film growth shows anomalous growth behaviour. These new growth behaviours with two processes result from the gradual change of molecular orientation and the formation of grain boundaries, which conversely induce new molecular orientation, rapid roughening process, and the formation of nanobelt crystals. PMID:25801646

  17. Ion sputter textured graphite electrode plates

    NASA Technical Reports Server (NTRS)

    Curren, A. N.; Forman, R.; Sovey, J. S.; Wintucky, E. G. (Inventor)

    1983-01-01

    A specially textured surface of pyrolytic graphite exhibits extremely low yields of secondary electrons and reduced numbers of reflected primary electrons after impingement of high energy primary electrons. Electrode plates of this material are used in multistage depressed collectors. An ion flux having an energy between 500 iV and 1000 iV and a current density between 1.0 mA/sq cm and 6.0 mA/sq cm produces surface roughening or texturing which is in the form of needles or spires. Such textured surfaces are especially useful as anode collector plates in high tube devices.

  18. Frequency response measurements in battery electrodes

    NASA Technical Reports Server (NTRS)

    Thomas, Daniel L.

    1992-01-01

    Electrical impedance spectroscopy was used to investigate the behavior of porous zinc, silver, cadmium, and nickel electrodes. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two AgZn cells, one apparently good and the other bad. The impedance data was fit to equivalent circuit models.

  19. Silver Doped Titanium Dioxide Humidity Sensor

    NASA Astrophysics Data System (ADS)

    Hooshiar Zare, Ali; Mohammadi, Somayye

    2011-02-01

    The effect of silver doping on the sensitivity, dynamic range and the response time of a titanium dioxide-based resistive humidity sensor is studied. Sample pallets were prepared by sintering the dry pressed samples at 900°C in air. Silver was added to the ceramic raw material in the form of AgNO3 which was decomposed during the sintering process. Large area silver electrodes were deposited on the sintered disks by paste printing. The resistance and the response time of the various pallets containing different additive levels were measured at relative humidity range of 4-100%. Silver doping, substantially increased the sensitivity to the ambient humidity. Moreover, it resulted in faster responses; the response time of the silver added pallets were about four times shorter than the pure ones.

  20. Recovering Silver from Photographic Process Wastes

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Adaikkalam, P.; Abdul Kader, J. A. M.; Visvanathan, S.

    1990-10-01

    Spent color bleach-fix solution (CBFS), a product of photographic processing operations, is a potential source of silver. Of the extraction reactors used in recovering this silver, the rotating cylindrical electrode (RCE) has an advantage in that it provides improved mass transfer with an extended effective surface area. In addition, the application of a potentiostatic technique allows the silver deposition reaction to take place preferentially, without the formation of silver sulfide. The process consists of prior physical treatment, subsequent chemical reduction of the ferric-EDTA (ethylene diamine tetra-acetic acid) complex present in the CBFS with sodium dithionite (monitored by measuring the redox potential of Fe3+/Fe2+ couple), followed by electrodeposition of silver in a divided cell using a cation exchange membrane. The combined procedure results in increased current efficiency and reduced electrolysis time.

  1. Electron transfer in silver telluride melt

    SciTech Connect

    Glazov, V.M.; Burkhanov, A.S.

    1987-06-01

    Electron transfer in silver telluride melt was studied experimentally at different temperatures. The method used to study electron transfer and thermodiffusion is based on Onsager's theory and consists of measuring the electrodiffusion potential which varies as a function of time in the system formed by the liquid semiconductor and the neutral metallic electrodes. The effective charges and the average coefficients of diffusion of silver ions were calculated and the ionic component of the total electrical conductivity of Ag/sub 2/Te melt was evaluated. It was observed that the indicated characteristics vary systematically in the series of silver chalcogenides with anionic substitution. The negative temperature coefficient of electrical conductivity in silver sulfide and silver selenide melts was explained.

  2. Microtitrimetry by differential electrolytic potentiometry using metallic electrodes and nanomaterials modified metallic electrodes

    NASA Astrophysics Data System (ADS)

    Amro, Abdulaziz Nabil

    For the first time silver wire electrodes have been coated with carbon nanotubes using floating catalyst chemical vapor deposition (CVD) method. The production of CNTs has been conducted in a horizontal tubular reactor. Acetylene gas was used as a carbon source. Ferrocene has been used as a catalyst precursor for the growth of CNT. Different parameters have been optimized to get a high yield of CNTs and ensure their growth on the silver electrodes using univariate method. The parameters studied include the hydrogen flow rate, acetylene flow rate, temperature of the furnace, time of the reaction and the location of the electrodes in the reactor tube. The optimum conditions for those parameters were: for hydrogen and acetylene, the flow rates were 25 mL /min and 75 mL / min respectively. The furnace temperature was found to be 700 °C and the reaction time was 15 minutes. Regarding the location of the silver wires it should be located in the first 10 cm of the front side of the tube. Scanning electron microscopy (SEM) and transition electron microscopy (TEM) have been used to characterize carbon on silver electrodes. According to the experimental results, TEM figures show that CNT produced on Silver wire is multiwall carbon nanotubes MWCNT. Silver electrodes either pure or coated with CNT were used as indicating systems in micro titration using both dc differential electrolytic potentiometry (DEP) and mark-space bias DEP techniques. All types of titrimetric reactions were investigated using different types of electrodes like Pt and gold for oxidation reduction titrations, antimony electrodes for acid base titrations, silver electrodes for precipitation titrations in addition to Ag-CNT electrodes. End points at volumes of 1 microL were determined. Different parameters were optimized like the current density, the percentage bias, the volume of the sample and the concentrations of the reactants. Microtitrimetry has been applied on several types of analytes; Ferrous

  3. Biomedical engineering tasks. [electrode development for electrocardiography and electroencephalography

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Electrocardiographic and vectorcardiographic bioinstrumentation work centered on the development of a new electrode system harness for Project Skylab. Evaluation of several silver electrode configurations proved superior impedance voltage performance for silver/silver chloride electrodes mounted flush by using a paste adhesive. A portable ECG processor has been designed and a breadboard unit has been built to sample ECG input data at a rate of 500 samples per second for arrhythmia detection. A small real time display driver program has been developed for statistical analysis on selected QPS features. Engineering work on a sleep monitoring cap assembly continued.

  4. Anomalous scaling behavior and surface roughening in molecular thin-film deposition

    SciTech Connect

    Yim, S.; Jones, T. S.

    2006-04-15

    The thin film growth dynamics of a molecular semiconductor, free-base phthalocyanine (H{sub 2}Pc), deposited by organic molecular beam deposition, has been studied by atomic force microscopy (AFM) and height difference correlation function (HDCF) analysis. The measured dynamic scaling components ({alpha}{sub loc}=0.61{+-}0.12, {beta}=1.02{+-}0.08, and 1/z=0.72{+-}0.13) are consistent with rapid surface roughening and anomalous scaling behavior. A detailed analysis of AFM images and simple growth models suggest that this behavior arises from the pronounced upward growth of crystalline H{sub 2}Pc mounds during the initial stages of thin film growth.

  5. A surface plasmon model for laser ablation of Ag sup + ions from a roughened Ag surface

    SciTech Connect

    Ritchie, R.H. Tennessee Univ., Knoxville, TN . Dept. of Physics); Manson, J.R. . Dept. of Physics); Echenique, P.M. . Faculdad de Quimica)

    1991-01-01

    Experimental work by Shea and Compton suggests that Ag{sup +} ions emitted from a roughened Ag surface irradiated by a nanosecond or picosecond laser beam may absorb the full energy of the Ag surface plasmon. We have modeled this process under the assumption that it proceeds through an inverse bremsstrahlung-type absorption of the SP quantum by Ag{sup +} ion which also undergoes a small-impact parameter collision with another ion or atom in the vicinity of the surface. We give a quantitative estimate of the absorption probability and find reasonable agreement with the Shea-Compton results. 8 refs., 2 figs.

  6. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  7. Kinetic Roughening and Energetics of Tetragonal Lysozyme Crystal Growth: A Preliminary Atomic Force Microscopy Investigation

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

    2004-01-01

    We examined particulars of crystal growth from measurements obtained at both microscopic and molecular levels. The crystal growth measurements performed at the microscopic level are well characterized by a model that balances the flux of macromolecules towards the crystal surface with the flux of the crystal surface. Numerical evaluation of model with measurements of crystal growth, in time, provided accurate estimates for the average growth velocities. Growth velocities thus obtained were also interpreted using well-established phenomenological theories. Moreover, we find that microscopic measurements of growth velocity measurements obtained as a function of temperature best characterizes changes in crystal growth modes, when present. We also examined the possibility of detecting a change in crystal growth modes at the molecular level using atomic force microscopy, AFM. From preliminary AFM measurements performed at various supersaturations, we find that magnitude of surface height fluctuations, h(x), increases with supersaturation. Further examination of surface height fluctuations using methods established for fluctuation spectroscopy also enabled the discovery of the existence of a characteristic length, c, which may possibly determine the mode of crystal growth. Although the results are preliminary, we establish the non- critical divergence of 5 and the root-mean-square (rms) magnitude of height-height fluctuations as the kinetic roughening transition temperatures are approached. Moreover, we also examine approximate models for interpreting the non-critical behavior of both 6 and rms magnitude of height-height fluctuations, as the solution supersaturation is increased towards the kinetic roughening supersaturation.

  8. Stochastic dynamics and phase-field roughening in optomechanical oscillator arrays

    NASA Astrophysics Data System (ADS)

    Lauter, Roland; Mitra, Aditi; Marquardt, Florian

    We consider arrays of coupled optomechanical systems, each of which consists of a laser-driven optical mode interacting with a mechanical (vibrational) mode. For sufficiently strong laser driving, the mechanical modes can settle into stable finite-amplitude oscillations on a limit cycle. We study the collective classical nonlinear dynamics of the phases of these oscillators, which is effectively described by an extension of the well-known Kuramoto model. In this extended model, we study the effect of noise on the dynamics in the case of homogeneous-phase initial conditions. We analytically establish a connection to the physics of surface growth as described by the Kardar-Parisi-Zhang model. Simulations of one-dimensional arrays of our model indeed show roughening of the phase field and universal scaling of the phase-field width. In contrast to the continuum Kardar-Parisi-Zhang model, our model is a genuine lattice model. We discuss interesting effects due to this difference, including crossover timescales and the role of instabilities of the roughening process.

  9. Morphological switching in synchrotron-radiation-excited Ge homoepitaxy: Transition from kinetic roughening to smoothing

    SciTech Connect

    Akazawa, Housei

    2005-05-15

    The surface morphology of Ge films during GeH{sub 4}-source molecular beam epitaxy on a Ge(100) substrate is dramatically changed through irradiation with synchrotron radiation (h{nu}>100 eV). At temperatures below 300 deg. C, a two-dimensionally flat film continues to grow with the surface tightly passivated by a GeH{sub x} hydride layer. At temperatures above 350 deg. C, dangling bonds are partially terminated with hydrogen atoms while Ge adatoms are highly mobile, resulting in a nonuniform nucleation that creates the islands. Small islands merge into a few-hundred-nanometer-tall islands surrounded by the (113)-face sidewalls. This kinetic roughening continues until the nucleation on the (001) plane ceases due to the buildup of the GeH{sub x} layer. Once the surface free energy is minimized by the hydrogen termination, flattening of the islands proceeds to reduce the chemical potential of the system. The valleys between the islands are preferentially filled, and the film is eventually converted into a smooth epilayer with no memory of the initial roughening.

  10. Preliminary flight prototype silver ion monitoring system, addendum

    NASA Technical Reports Server (NTRS)

    Wilson, R. I.

    1975-01-01

    A number of electrode fabrication techniques are investigated, to achieve an electrode meeting shuttle mission requirements for functional life and stability as well as accuracy and precision of measurement. The instability of a silver bromide column when employed in a closed loop calibration scheme is discussed.

  11. Fabrication and testing of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Debicarri, D. J.; Charkey, A.

    1978-01-01

    Silver electrodes containing various additives were fabricated and tested in single electrode cells in order to improve the electrochemical utilization of sintered silver cathodes in Ag-H2 aerospace batteries. A standard stack arrangement was used which featured a NASA-developed organic-inorganic separator. All cells were cycled in a regime designed to remove 75% of the cells nominal capacity based on 3.3 gms/AHr Ag utilization. In cases where performance degradation was observed, the main feature mode appeared to be corrosion of either the expanded silver current collector or the connection between the silver electrode and the electrode tab. Promising silver electrodes from single electrode studies were used in the construction of 35 AHr Ag-H2 cells. Two such cells were constructed and installed in heavy walled pressure vessels for testing. Based on the data obtained from all cells tested during the program, four lightweight 35 AHr cells were fabricated. During acceptance testing these cells yielded an average gravimetric energy density of 30 WHr/1b.

  12. Design and fabrication of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Klein, M. G.

    1975-01-01

    The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

  13. Metal nanowire-graphene composite transparent electrodes

    NASA Astrophysics Data System (ADS)

    Mankowski, Trent; Zhu, Zhaozhao; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine; Mansuripur, Masud; Falco, Charlies M.

    2014-10-01

    Silver nanowires with 40 nm diameter and copper nanowires with 150 nm diameter were synthesized using low-temperature routes, and deposited in combination with ultrathin graphene sheets for use as transparent conductors. A systematic and detailed analysis involving nature of capping agent for the metal nanowires, annealing of deposited films, and pre-treatment of substrates revealed critical conditions necessary for preparing high performance transparent conducting electrodes. The best electrodes show ~90% optical transmissivity and sheet resistance of ~10 Ω/□, already comparable to the best available transparent electrodes. The metal nanowire-graphene composite electrodes are therefore well suited for fabrication of opto-electronic and electronic devices.

  14. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, S.P.; Woods, R.W.

    1998-08-11

    A process is disclosed for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750 C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5--3000 ppm in order to obtain a desired composition in the resulting composite. 2 figs.

  15. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, Siba P.; Woods, Robert W.

    1998-01-01

    A process for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750.degree. C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5-3000 ppm in order to obtain a desired composition in the resulting composite.

  16. Silver nanoparticles-coated glass frits for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  17. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor.

    PubMed

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun

    2015-12-15

    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors. PMID:26258877

  18. Analysis of Surface Roughening in AA6111 Automotive Sheet Under Pure Bending

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Zhao, P. Z.; Jin, H.; Wu, P. D.; Lloyd, D. J.

    2016-02-01

    The finite element method is used to numerically simulate the topographic development in an aluminum sheet, AA6111, under pure bending. The measured electron backscatter diffraction data are directly incorporated into the finite element model, and the constitutive response at an integration point is described by the single crystal plasticity theory. The effects of strain-rate sensitivity, work hardening, and imposed initial surface roughness on surface roughening are studied. It is found that the grains in top surface layers of the sheet play a big role in controlling the outer surface roughness due to the strain gradient across sheet thickness in bending, while the grain size and texture of the surface layers have a direct impact on finishing surface qualities.

  19. Time-dependent couplings and crossover length scales in nonequilibrium surface roughening

    NASA Astrophysics Data System (ADS)

    Pradas, Marc; López, Juan M.; Hernández-Machado, A.

    2007-07-01

    We show that time-dependent couplings may lead to nontrivial scaling properties of the surface fluctuations of the asymptotic regime in nonequilibrium kinetic roughening models. Three typical situations are studied. In the case of a crossover between two different rough regimes, the time-dependent coupling may result in anomalous scaling for scales above the crossover length. In a different setting, for a crossover from a rough to either a flat or damping regime, the time-dependent crossover length may conspire to produce a rough surface, although the most relevant term tends to flatten the surface. In addition, our analysis sheds light into an existing debate in the problem of spontaneous imbibition, where time-dependent couplings naturally arise in theoretical models and experiments.

  20. An experimental study of microwave scattering from rain- and wind-roughened seas

    NASA Technical Reports Server (NTRS)

    Bliven, L. F.; Giovanangeli, J.-P.

    1993-01-01

    This paper investigates radar cross-section (RCS) characteristics of rain- and wind-roughened sea-surfaces. We conducted experiments in laboratory wind-wave tanks using artificial rain. The study includes light rain rates, light wind speeds, and combinations of these. A 36 Ghz scatterometer was operated at 30 deg incidence angle and with vertical polarization. RCS data were obtained not only with the scatterometer pointing up-wind but also as a function of azimuthal angle. We use a scatterometer rain and wind model SRWM-1, which relates the total average RCS in storms to the sum of the average RCS due to rain plus the average RCS due to wind. Implications of the study for operational monitoring of wind in rainy oceanic areas by satellite-borne instruments is discussed.

  1. Electrochemically Created Highly Surface Roughened Ag Nanoplate Arrays for SERS Biosensing Applications

    PubMed Central

    Slotcavage, Daniel; Mai, John D.; Guo, Feng; Li, Sixing; Zhao, Yanhui; Lei, Yong; Cameron, Craig E.

    2014-01-01

    Highly surface-roughened Ag nanoplate arrays are fabricated using a simple electrodeposition and in situ electrocorrosion method with inorganic borate ions as capping agent. The electrocorrosion process is induced by a change in the local pH value during the electrochemical growth, which is used to intentionally carve the electrodeposited structures. The three dimensionally arranged Ag nanoplates are integrated with substantial surface-enhanced Raman scattering (SERS) hot spots and are free of organic contaminations widely used as shaping agents in previous works, making them excellent candidate substrates for SERS biosensing applications. The SERS enhancement factor of the rough Ag nanoplates is estimated to be > 109. These Ag nanoplate arrays are used for SERS-based analysis of DNA hybridization monitoring, protein detection, and virus differentiation without any additional surface modifications or labelling. They all exhibit an extremely high detection sensitivity, reliability, and reproducibility. PMID:25383191

  2. Roughening and Preroughening of Diamond-Cubic {l_brace}111{r_brace} Surfaces

    SciTech Connect

    Woodraska, D.L.; Jaszczak, J.A.

    1997-01-01

    A solid-on-solid model for {l_brace}111{r_brace} surfaces of diamond-cubic materials that correctly takes into account the diamond-cubic crystal structure has been developed for Monte Carlo simulation. In addition to a roughening transition at temperature T{sub R}, a distinct preroughening transition at T{sub PR}{approx}0.43T{sub R} is indicated by divergences in the surface specific heat and order-parameter susceptibility. Preroughening appears to arise naturally in our nearest-neighbor bond model from the entropic freedom available in the nontrivial crystal structure. Preroughening is shown to dramatically lower the nucleation barrier for growth and etching at low driving forces. {copyright} {ital 1997} {ital The American Physical Society}

  3. Roughening of an interface in a system with surface or bulk disorder

    NASA Astrophysics Data System (ADS)

    Corberi, Federico; Lippiello, Eugenio; Zannetti, Marco

    2016-05-01

    We study numerically the roughening properties of an interface in a two-dimensional Ising model with either random bonds or random fields, which are representative of universality classes where disorder acts only on the interface or also away from it, in the bulk. The dynamical structure factor shows a rich crossover pattern from the form of a pure system at large wavevectors k, to a different behavior, typical of the kind of disorder, at smaller k's. For the random field model a second crossover is observed from the typical behavior of a system where disorder is only effective on the surface, as the random bond model, to the truly large scale behavior, where bulk-disorder is important, that is observed at the smallest wavevectors.

  4. Convective Heat Transfer from Castings of Ice Roughened Surfaces in Horizontal Flight

    NASA Technical Reports Server (NTRS)

    Dukhan, Nihad; Vanfossen, G. James, Jr.; Masiulaniec, K. Cyril; Dewitt, Kenneth J.

    1995-01-01

    A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This technique was applied to a series of ice shapes that were grown in the NASA Lewis Icing Research Tunnel on flat plates. Eight different types of ice growths, characterizing different types of roughness, were obtained from these plates, from which aluminum castings were made. Test strips taken from these castings were outfitted with heat flux gages, such that when placed in a dry wind tunnel, they could be used to experimentally map out the convective heat transfer coefficient in the direction of flow from the roughened surfaces. The effects on the heat transfer coefficient for parallel flow, which simulates horizontal flight, were studied. The results of this investigation can be used to help size heaters for wings, helicopter rotor blades, jet engine intakes, etc., or de-icing for anti-icing applications where the flow is parallel to the iced surface.

  5. Analysis for leakage and rotordynamic coefficients of surface roughened tapered annular gas seals

    NASA Technical Reports Server (NTRS)

    Nelson, C. C.

    1984-01-01

    In order to soften the effects of rub, the smooth stators of turbine gas seals are sometimes replaced by a honeycomb surface. This deliberately roughened stator and smooth rotor combination retards the seal leakage and may lead to enhanced rotor stability. However, many factors determine the rotordynamic coefficients and little is known as to the effectiveness of these honeycomb seals under various changes in the independent seal parameters. An analytical-computational method to solve for the rotordynamic coefficients of this type of compressible-flow seal is developed. The governing equations for surface roughned tapered annular gas seals are based on a modified Hirs' turbulent bulk flow model. A perturbation analysis is employed to develop zeroth and first-order perturbation equations. These equations are numerically integrated to solve for the leakage, pressure, density, and velocity for small motion of the shaft about the centered position. The resulting pressure distribution is then integrated to find the corresponding rotor-dynamic coefficients.

  6. Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Bentz, Daniel N.; Betush, William; Jackson, Kenneth A.

    2003-01-01

    In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (kMC) simulation with diffusion by pair exchange only in the liquid phase. Entropies of fusion are first chosen to fit the surface roughness of the pure materials, and the bond energies are derived from the equilibrium phase diagram, by treating the solid and liquid as regular and ideal solutions respectively. A simple cubic lattice oriented in the {100} direction is used. Growth of the rods is initiated from columns of pure B material embedded in an A matrix, arranged in a close packed array with semi-periodic boundary conditions. The simulation cells typically have dimensions of 50 by 87 by 200 unit cells. Steady state growth is compliant with the Jackson-Hunt model. In the kMC simulations, using the spin-one Ising model, growth of each phase is faceted or nonfaceted phases depending on the entropy of fusion. There have been many studies of the surface roughening transition in single component systems, but none for binary alloy systems. The location of the surface roughening transition for the phases of a eutectic alloy determines whether the eutectic morphology will be regular or irregular. We have conducted a study of surface roughness on the spin-one Ising Model with diffusion using kMC. The surface roughness was found to scale with the melting temperature of the alloy as given by the liquidus line on the equilibrium phase diagram. The density of missing lateral bonds at the surface was used as a measure of surface roughness.

  7. Extended sensitivity for the calcium selective electrode.

    PubMed

    Morton, R W; Chung, J K; Miller, J L; Charlton, J P; Fager, R S

    1986-09-01

    Sensitivity of calcium-selective electrodes heretofore has been limited to calcium concentrations above 10(-8) M in the absence of competing ions. We describe the use of calcium buffers to stabilize the free calcium in the reference electrode. Electrode calibration is linear to 10(-8) M and is curvilinear to 10(-11) M in the presence of 0.1 M ionic strength. Selectivity with respect to competing cations, magnesium, potassium, sodium, and hydrogen is preserved. Electrode response time is less than 2 s for small changes in calcium activity. Response range is linear over 9 log units of calcium activity. Potential-time stability is less than 10 mV/h at saturation currents. Although the silver-silver chloride terminals are photosensitive throughout the visible and near-ultraviolet regions, housing the reference and indifferent in opaque barrels avoids false photovoltaic response. PMID:3777438

  8. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  9. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  10. Photoelectrolytic production of hydrogen using semiconductor electrodes

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Walker, G. H.

    1976-01-01

    Experimental data for the photoelectrolytic production of hydrogen using GaAs photoanodes was presented. Four types of GaAs anodes were investigated: polished GaAs, GaAs coated with gold, GaAs coated with silver, and GaAs coated with tin. The maximum measured efficiency using a tungsten light source was 8.9 percent for polished GaAs electrodes and 6.3 percent for tin coated GaAs electrodes.

  11. An analysis of LDEF-exposed silvered FEP teflon thermal blanket material

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.

    1991-01-01

    The characterization of selected silvered fluorinated ethylene propylene (FEP) teflon thermal blanket material which received 5 years and 9 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. X-ray photoelectron spectroscopy, infrared, and thermal analyses did not detect a significant change at the molecular level as the result of this exposure. However, various microscopic analyses revealed a roughening of the coating surface due to atomic oxygen erosion which resulted in some materials changing from specular reflectors of visible radiation to diffuse reflectors. The potential effect of silicon-containing molecular contamination on these materials is addressed.

  12. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  13. Partitioning of silver and chemical speciation of free Ag in soils amended with nanoparticles

    PubMed Central

    2013-01-01

    Background Knowledge about silver nanoparticles in soils is limited even if soils are a critical pathway for their environmental fate. In this paper, speciation results have been acquired using a silver ion selective electrode in three different soils. Results Soil organic matter and pH were the most important soil properties controlling the occurrence of silver ions in soils. In acidic soils, more free silver ions are available while in the presence of organic matter, ions were tightly bound in complexes. The evolution of the chemical speciation of the silver nanoparticles in soils was followed over six months. Conclusion During the first few hours, there appeared to be a strong sorption of the silver with soil ligands, whereas over time, silver ions were released, the final concentration being approximately 10 times higher than at the beginning. Ag release was associated with either the oxidation of the nanoparticles or a dissociation of adsorbed silver from the soil surfaces. PMID:23617903

  14. Working Electrodes

    NASA Astrophysics Data System (ADS)

    Komorsky-Lovrić, Šebojka

    In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution; however, solid electrolytes and ionic melts can be used as well. The term "electrode" is also used in a technical sense, meaning the electronic conductor only. If not specified otherwise, this meaning of the term "electrode" is the subject of the present chapter. In the simplest case the electrode is a metallic conductor immersed in an electrolyte solution. At the surface of the electrode, dissolved electroactive ions change their charges by exchanging one or more electrons with the conductor. In this electrochemical reaction both the reduced and oxidized ions remain in solution, while the conductor is chemically inert and serves only as a source and sink of electrons. The technical term "electrode" usually also includes all mechanical parts supporting the conductor (e.g., a rotating disk electrode or a static mercury drop electrode). Furthermore, it includes all chemical and physical modifications of the conductor, or its surface (e.g., a mercury film electrode, an enzyme electrode, and a carbon paste electrode). However, this term does not cover the electrolyte solution and the ionic part of a double layer at the electrode/solution interface. Ion-selective electrodes, which are used in potentiometry, will not be considered in this chapter. Theoretical and practical aspects of electrodes are covered in various books and reviews [1-9].

  15. Surface enhanced Raman scattering of melamine on silver substrate: An experimental and DFT study.

    PubMed

    An, Nguyen Thi Thai; Dao, Duy Quang; Nam, Pham Cam; Huy, Bui The; Nhung Tran, Hong

    2016-12-01

    Surface enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique that allows amplifying weak Raman signals by the excitation of localized surface plasmons. In this paper, we used nanoscale roughened silver surface to enhance Raman signals of melamine analyte. Silver nanoparticles were synthesized by wet-chemical method and employed for SERS measurement. Theoretically, optimized geometries and vibrational frequencies of melamine and melamine absorbed on silver-cluster surface were calculated by using the B3LYP/6-31G(d) method. Then, the predicted spectrograms are compared with the experimental Raman spectra. As a result, Raman signals of melamine were dramatically enhanced by using obtained silver nanoparticles as the substrate. Typical peaks of melamine at 676 and 983cm(-1) were enhanced and could be obviously observed in experiments. The calculated vibrational frequencies seem to relatively coincide with the experimental values. SERS effect of melamine on nanoscale silver was also explained by analyzing molecular frontier orbitals (HOMO and LUMO) melamine-silver complexes. PMID:27387126

  16. Fabrication of an Inexpensive Ion-Selective Electrode.

    ERIC Educational Resources Information Center

    Palanivel, A.; Riyazuddin, P.

    1984-01-01

    The preparation and performance of a graphite (silver/copper sulfide) electrode is described. This rod, extracted from a used dry cell, is an acceptable substitute for ion-selective electrodes after it has been cleaned by abrasion followed by an overnight treatment with hydrochloric acid. (JN)

  17. Improved electrode gives high-quality biological recordings

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Lippitt, M. W.

    1964-01-01

    To obtain high quality waveforms from a subject engaged in physical activity, an improved electrode assembly has been devised. This consists of a cup containing an electrically conductive paste and a silver electrode. The paste maintains contact between the skin and the plate.

  18. Substrate effects and diffusion dominated roughening in Cu2O electrodeposition

    NASA Astrophysics Data System (ADS)

    Brandt, I. S.; Zoldan, V. C.; Stenger, V.; Plá Cid, C. C.; Pasa, A. A.; Oliveira, T. J.; Aarão Reis, F. D. A.

    2015-10-01

    Cuprous oxide (Cu2O) films from 25 nm to 1500 nm were electrodeposited on n-Si(100) and Ni/n-Si(100) substrates from aqueous solution at room temperature. X-ray diffraction and transmission electron microscopy imaging show that the Cu2O structure and morphology are strongly affected by the substrate choice, with V shape and U shape columnar growth on n-Si(100) and Ni/n-Si(100), respectively. Atomic force microscopy reveals the presence of rounded grains at the surface in both cases. Anomalous and normal roughening are observed in films grown on n-Si and Ni, respectively, but estimates of scaling exponents are not conclusive. On the other hand, the distributions of local heights, roughness, and extremal heights show good agreement with those of the fourth order linear stochastic equation of Mullins and Herring (MH). Thus, surface dynamics in both systems is dominated by diffusion of adsorbed molecules, with no large scale effect of possible inhomogeneities in mass flux from the solution or in reaction and adsorption rates. In growth on n-Si substrates, the noise amplitude of the MH equation increases in time as t0.8 , while the coefficient of the curvature-related term is time-independent. Step edge energy barriers restrict the mass flux across grain boundaries, thus a broad size distribution of initial grains leads to coarsening of the larger ones. This explains their V shape in the thickest films and establishes a connection with the anomalous roughening. These effects are reduced in films grown on Ni/n-Si, which initially have much larger grains with narrower size distributions and, consequently, smaller fluctuations in coarse grained growth rates. Thus, despite the relevance of electrochemical conditions for Cu2O films to grow and their influence on crystallographic orientation, large scale surface features are determined by physical properties of the material and its interactions with the substrate, with a universal microscopic dynamics similar to vapor

  19. Real-Space Direct Visualization of the Layer-Dependent Roughening Transition in Nanometer-Thick Pb Films

    NASA Astrophysics Data System (ADS)

    Calleja, F.; Passeggi, M. C. G., Jr.; Hinarejos, J. J.; de Parga, A. L. Vázquez; Miranda, R.

    2006-11-01

    By means of variable-temperature scanning tunneling microscopy and spectroscopy we studied the thickness-dependent roughening temperature of Pb films grown on Cu(111), whose electronic structure and total energy is controlled by quantum well states created by the spatial confinement of electrons. Large scale STM images are employed to quantify the layer population, i.e., the fraction of the surface area covered by different Pb thicknesses, directly in the real space as a function of temperature. The roughening temperature oscillates repeatedly with bilayer periodicity plus a longer beating period, mirroring the thickness dependence of surface energy calculations. Conditions have been found to stabilize at 300 K Pb films of particular magic thicknesses, atomically flat over microns.

  20. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  1. Proper Orthogonal Decomposition Analysis of Turbulent Jet Impingement on Rib-roughened Surface

    NASA Astrophysics Data System (ADS)

    Lam, Prasanth Anand Kumar; Karaiyan, Arul Prakash; Thermo-Fluid Dynamics Laboratory Team

    2015-11-01

    A Proper Orthogonal Decomposition (POD) analysis on turbulent flow dynamics of confined slot jet impinging on rib-roughened surface is numerically investigated. The data for POD analysis has been obtained by solving mass, momentum and energy equations in Cartesian framework using Streamline Upwind/Petrov-Galerkin Finite element method. Further, turbulent kinetic energy (k) and its dissipation rate (ɛ) are modeled using standard k- ɛ turbulence model with standard wall functions. POD is applied to computational data for a wide range of Reynolds number (Re) = 5000 - 30000 and non-dimensional channel height (H/L) = 0.5 - 4.0 to reveal large scale vortical structures in the flow field. The simulated results demonstrate a better understanding on effect of turbulence and its influence on individual vortical structures for enhancement of heat transfer. The enhancement of heat transfer in stagnation region due to combined effect of oscillation in impingement position caused by large vortical structures and strong acceleration of fluid during impingement is quantified. Furthermore, non-dimensional correlations have been derived for pressure drop and Surface averaged Nusselt number.

  2. Long structures in a turbulent boundary layer with a rod-roughened wall

    NASA Astrophysics Data System (ADS)

    Kim, Jung Hoon; Lee, Jae Hwa

    2015-11-01

    Direct numerical simulation (DNS) of a turbulent boundary layer (TBL) over a rod-roughened wall is performed with long streamwise domain to examine streamwise scale growth mechanism of streamwise velocity fluctuating structures. The surface roughness is the two-dimensional (2-D) rod arranged regularly in the streamwise direction. Inspection of the instantaneous flow fields and streamwise two-point spatial correlations of the streamwise velocity fluctuations shows that the streamwise and spanwise length scales of the structures over the rough wall are generally larger than those over the smooth wall, while the spanwise inclination angle to the streamwise direction (helix angle) is smaller over the rough wall. Inspection of time-evolving instantaneous fields clearly exhibits that adjacent long structures combine to form a longer structure by spanwise merging process over the rough wall, and the occurrence of the spanwise merging for the streamwise scale growth is expected to be more active over the rough wall due to turbulent scales generated by the 2-D roughness. This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2014R1A1A2057031) and 2015 Research Fund (1.150033.01) of UNIST.

  3. Current at domain walls, roughly speaking: nanoscales studies of disorder roughening and conduction

    NASA Astrophysics Data System (ADS)

    Paruch, Patrycja

    2013-03-01

    Domain walls in (multi)ferroic materials are the thin elastic interfaces separating regions with different orientations of magnetisation, electric polarisation, or spontaneous strain. Understanding their behaviour, and controlling domain size and stability, is key for their integration into applications, while fundamentally, domain walls provide an excellent model system in which the rich physics of disordered elastic interfaces can be accesses. In addition, domain walls can present novel properties, quite different from those of their parent materials, making them potentially useful as active components in future nano-devices. Here, we present our atomic force microscopy studies of ferroelectric domain walls in epitaxial Pb(Zr0.2Ti0.8)O3 and BiFeO3 thin films, in which we use piezorespose force microscopy to show unusual domain wall roughening behaviour, with very localised disorder regions in the sample leading to a complex, multi-affine scaling of the domain wall shape. We also show the effects of temperature, environmental conditions, and defects on switching dynamics and domain wall roughness. We combine these observations with parallel conductive-tip atomic force microscopy current measurements, which also show highly localised variations in conduction, and highlight the key role played by oxygen vacancies in the observed domain wall conduction.

  4. Computational prediction of heat transfer to gas turbine nozzle guide vanes with roughened surfaces

    SciTech Connect

    Guo, S.M.; Jones, T.V.; Lock, G.D.; Dancer, S.N.

    1998-04-01

    The local Mach number and heat transfer coefficient over the aerofoil surfaces and endwalls of a transonic gas turbine nozzle guide vane have been calculated. the computations were performed by solving the time-averaged Navier-Stokes equations using a fully three-dimensional computational code (CFDS), which is well established at Rolls-Royce. A model to predict the effects of roughness has been incorporated into CFDS and heat transfer levels have been calculated for both hydraulically smooth and transitionally rough surfaces. The roughness influences the calculations in two ways; first the mixing length at a certain height above the surface is increased; second the wall function used to reconcile the wall condition with the first grid point above the wall is also altered. The first involves a relatively straightforward shift of the origin in the van Driest damping function description, the second requires an integration of the momentum equation across the wall layer. A similar treatment applies to the energy equation. The calculations are compared with experimental contours of heat transfer coefficient obtained using both thin-film gages and the transient liquid crystal technique. Measurements were performed using both hydraulically smooth and roughened surfaces, and at engine-representative Mach and Reynolds numbers. The heat transfer results are discussed and interpreted in terms of surface-shear flow visualization using oil and dye techniques.

  5. Numerical sensitivity analysis of 3- and 2- dimensional rib-roughened channels

    NASA Astrophysics Data System (ADS)

    Keshmiri, Amir

    2012-07-01

    Rough surfaces have been used as a tool to enhance heat transfer by increasing the level of turbulence mixing in the flow. In numerically simulating such flows, it is common to simulate a 3D rib-roughened channel with a 2D domain in order to reduce the computational time and power. The main purpose of the present work is to investigate the accuracy of the above approximation. In order to do so, initially a 3D channel is simulated using Reynolds-Averaged Navier-Stokes technique and comparison is made against 2D simulations as well as experimental data. In addition, the effects of rib thermal boundary condition and near-wall treatments are also investigated. All computations are undertaken using the commercial CFD code `STAR-CD'. The Reynolds number, based on the channel bulk velocity and hydraulic diameter, is 30,000. Two low-Reynolds-number linear Eddy-Viscosity Models, namely the Lien-Chen-Leschziner k - ɛ model and a variant of Durbin's v 2 - f formulation are used. In the CFD simulations reported here, the focus is on the experimental data of Rau et al. (ASME J Turbomach 120:368-375, 1998). It was found that the present results for a 3D channel are in relatively good agreement with the data. It was also shown that a 2D channel can be used to represent the flow in the centre-line of a 3D channel with relatively good accuracy.

  6. Meniscus arrest dominated imbibition front roughening in porous media with elongated pores

    NASA Astrophysics Data System (ADS)

    Rieger, Heiko; Thome, Christian; Sadjadi, Zeinab

    2015-09-01

    During spontaneous imbibition, a wetting liquid is drawn into a porous medium by capillary forces. Recently, anomalous scaling properties of front broadening during spontaneous imbibition of water in Vycor glass, a nanoporous medium, were reported. The mean height and the width of the propagating front increase with time t both proportional to t1/2. We argue that this anomalously large roughening exponent of β = 1/2 is due to long-lasting meniscus arrests, when at pore junctions the meniscus propagation in one or more branches comes to a halt when the Laplace pressure of the meniscus exceeds the hydrostatic pressure within the junction. From this hypothesis we derive the scaling relations for the emerging arrest time distribution in random pore networks and show that the average front width is proportional to the height yielding a roughness exponent of exactly β = 1/2 as measured in the Vycor glass imbibition experiments. Extensive simulations of a random pore network model confirm these predictions. Finally, using a microfluidic setup as well as molecular dynamics simulations on the nanoscale, the basic hypothesis of the scaling theory is confirmed by demonstrating the existence of arrest events in Y-shaped junctions, analyzing them quantitatively and comparing them with the theoretical predictions.

  7. Entanglement in correlated random spin chains, RNA folding and kinetic roughening

    NASA Astrophysics Data System (ADS)

    Rodríguez-Laguna, Javier; Santalla, Silvia N.; Ramírez, Giovanni; Sierra, Germán

    2016-07-01

    Average block entanglement in the 1D XX-model with uncorrelated random couplings is known to grow as the logarithm of the block size, in similarity to conformal systems. In this work we study random spin chains whose couplings present long range correlations, generated as gaussian fields with a power-law spectral function. Ground states are always planar valence bond states, and their statistical ensembles are characterized in terms of their block entropy and their bond-length distribution, which follow power-laws. We conjecture the existence of a critical value for the spectral exponent, below which the system behavior is identical to the case of uncorrelated couplings. Above that critical value, the entanglement entropy violates the area law and grows as a power law of the block size, with an exponent which increases from zero to one. Interestingly, we show that XXZ models with positive anisotropy present the opposite behavior, and strong correlations in the couplings lead to lower entropies. Similar planar bond structures are also found in statistical models of RNA folding and kinetic roughening, and we trace an analogy between them and quantum valence bond states. Using an inverse renormalization procedure we determine the optimal spin-chain couplings which give rise to a given planar bond structure, and study the statistical properties of the couplings whose bond structures mimic those found in RNA folding.

  8. Transparent and conductive electrodes based on unpatterned, thin metal films

    NASA Astrophysics Data System (ADS)

    O'Connor, Brendan; Haughn, Chelsea; An, Kwang-Hyup; Pipe, Kevin P.; Shtein, Max

    2008-12-01

    Transparent electrodes composed of ultrathin, unpatterned metal films are investigated in planar heterojunction (PHJ) and bulk heterojunction organic photovoltaic (OPV) cells. Optimal electrode composition and thickness are deduced from electrical and optical models and experiments, enabling a PHJ-OPV cell to be realized using a silver anode, achieving power conversion efficiency parity with an analogous cell that uses an indium tin oxide anode. Beneficial aspects of smooth, unpatterned metal films as transparent electrodes in OPV cells are also discussed in the text.

  9. Silver nanowires

    NASA Astrophysics Data System (ADS)

    Graff, A.; Wagner, D.; Ditlbacher, H.; Kreibig, U.

    2005-07-01

    Free silver nanowires were produced in aqueous electrolyte by a novel chemical reaction. Their diameters are about 27 nm, the lengths range up to more than 70 μm, yielding extreme length to thickness-ratios up to 2500. Their structure was identified by TEM analysis (SAED) and HRTEM to consist of a lattice aligned bundle of five monocrystalline rods of triangular cross-section forming an almost regular pentagonal cross-section. It is demonstrated that, for application purposes, single free nanowires can be mounted between contact areas. This manipulation is enabled by observing the nanowires in real time at atmosphere by Zsigmondy-Siedentopf farfield darkfield microscopy. Experimental results are presented concerning electrical dc conductivity and optical plasmon polariton excitation, the latter obtained from a single free wire without substrate and a single wire deposited on quartz glass. We also report about a present research cooperation with the Graz group of Aussenegg and Krenn which is devoted to investigate plasmon propagation in our Ag nanowires and to prove application possibilities as information guide fibers in analogy to optical fibers which may be integrated into micro- and nanoelectronic circuits.

  10. The Silver Halides

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  11. Colloidal Silver Products

    MedlinePlus

    ... can be dangerous to your health. What the Science Says About the Safety and Side Effects of ... homemade and commercial colloidal silver products. What the Science Says About the Effectiveness of Colloidal Silver Scientific ...

  12. 2D-patterning of self-assembled silver nanoisland films.

    PubMed

    Chervinskii, Semen; Reduto, Igor; Kamenskii, Alexander; Mukhin, Ivan S; Lipovskii, Andrey A

    2016-01-01

    The paper is dedicated to the recently developed by the authors technique of silver nanoisland growth, allowing self-arrangement of 2D-patterns of nanoislands. The technique employs silver out-diffusion from ion-exchanged glass in the course of annealing in hydrogen. To modify the silver ion distribution in the exchanged soda-lime glass we included the thermal poling of the ion-exchanged glass with a profiled electrode as an intermediate stage of the process. The resulting consequence consists of three steps: (i) during the ion exchange of the glass in the AgxNa1-xNO3 (x = 0.01-0.15) melt we enrich the subsurface layer of the glass with silver ions; (ii) under the thermal poling, the electric field displaces these ions deeper into the glass under the 2D profiled anodic electrode, the displacement is smaller under the hollows in the electrode where the intensity of the field is minimal; (iii) annealing in a reducing atmosphere of hydrogen results in silver out-diffusion only in the regions corresponding to the electrode hollows, as a result silver forms nanoislands following the shape of the electrode. Varying the electrode and mode of processing allows governing the nanoisland size distribution and self-arrangement of the isolated single nanoislands, pairs, triples or groups of several nanoislands-so-called plasmonic molecules. PMID:26765367

  13. Advancements in electrode design and laser techniques for fabricating micro-electrode arrays as part of a retinal prosthesis.

    PubMed

    Dodds, C W D; Schuettler, M; Guenther, T; Lovell, N H; Suaning, G J

    2011-01-01

    Retinal micro-electrode arrays (MEAs) for a visual prosthesis were fabricated by laser structuring of platinum (Pt) foil and liquid silicone rubber. A new design was created using a folding technique to create a multi-layered array from a single Pt sheet. This method allowed a reduction in both the electrode pitch, and the overall width of the array, while maintaining coplanar connection points for more stable interconnections to other components of the system. The design also included a section which could be rolled to create a cylindrical segment in order to minimise the size of the exit in the sclera after implantation. A picosecond mode-locked 532 nm laser system was investigated as a replacement for the nanosecond Q-switched 1064 nm laser currently in use. Trials showed that the ps system could produce high quality electrode tracks with a minimum pitch of 30 μm, less than 40% the pitch achievable with the ns laser. A method was investigated for the cutting of Pt foils without damaging the underlying silicone by laser machining to a depth just below the thickness of the foil. Initial samples showed promise with full penetration of the foil only occurring at cross points of the laser paths. The ps laser was also used to create roughened surfaces, in order to increase the electrochemical surface area of the electrodes. Surfaces were imaged using a scanning electron microscope, and compared to surfaces roughened with the ns laser. The ps laser was seen to offer a reduction in feature size, as well as an increase in control over the appearance of the electrode surface. PMID:22254389

  14. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  15. Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

    SciTech Connect

    Siw, Sin Chien; Chyu, Minking K.; Alvin, Mary Anne

    2013-03-01

    An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = [1/4]E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e., C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.

  16. Wear of gamma-crosslinked polyethylene acetabular cups against roughened femoral balls.

    PubMed

    McKellop, H; Shen, F W; DiMaio, W; Lancaster, J G

    1999-12-01

    Crosslinking of ultrahigh molecular weight polyethylene has been shown to markedly improve its wear resistance in clinical studies and laboratory tests using hip joint simulators. However, because most of the laboratory studies have been done under clean conditions using prosthesis-quality, highly polished counterfaces, there is concern regarding how well an intentionally crosslinked polyethylene acetabular cup will resist abrasion by a femoral ball that has been damaged by third-body abrasion in vivo. To investigate this, conventional and radiation crosslinked-remelted acetabular cups of ultra-high molecular weight polyethylene were tested in a hip joint simulator bearing against smooth femoral balls and against balls with moderate and severe roughening. Cups were tested with and without aging to accelerate any oxidative degradation. The crosslinked cups were produced by exposing extruded GUR 4150 bar stock of ultrahigh molecular weight polyethylene to 5 Mrad gamma radiation under a partial vacuum and then the bars were remelted to extinguish residual free radicals. Artificial aging at 70 degrees C under 5 atm oxygen for 14 days induced negligible oxidation in the crosslinked and remelted material. Against smooth balls, the wear of the crosslinked cups, with or without aging, averaged approximately 15% of that of the conventional cups. Against the moderately rough balls, the wear rate of the conventional cups was unchanged, whereas the wear rate increased slightly for the nonaged and aged crosslinked cups, but was still only 26% and 20% of that of the conventional cups, respectively. Against extremely rough balls, the mean wear rates increased markedly for each material such that during the final 1 million cycle interval, the average wear rates of the nonaged and the aged crosslinked cups were 72% and 47% of that of the conventional cups, respectively. That is, the crosslinked polyethylene showed substantially better wear resistance than conventional polyethylene

  17. In situ STM investigation of Ag(111) electrochemical roughening in perchlorate solutions

    NASA Astrophysics Data System (ADS)

    Aloisi, G.; Funtikov, A. M.; Guidelli, R.

    1993-11-01

    The surface structures generated by oxidation-reduction cycles (ORCs) on a well characterized silver (111) single crystal face have been examined by in situ STM. The ORCs, carried out in aqueous KClO 4, produce surface structures which span from atomic-scale clusters to large-scale features with linear dimensions of some hundreds of nanometers. While the surface structures produced by the ORC are stable at the most negative potentials, application of increasingly positive potentials causes a rearrangement of the surface with progressive predominance of the large-scale features over the small-scale ones, quite probably by a mechanism involving silver dissolution and redeposition of silver ions. This increase in dimensions is accompanied by a decrease in the SERS activity of the metal surface. The atomic-scale clusters, which are clearly visible by in situ STM at far negative potentials, are responsible for a substantial increase in Raman enhancement. Bumps with dimensions of the order of tens of nanometers, which are responsible for the excitation of local modes, are shown by in situ STM to persist at - 0.5 V/SCE. However, a further positive shift in potential causes a decrease both in their number and in the SERS activity.

  18. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  19. Electrical properties of metallic electrodes.

    PubMed

    Ragheb, T; Geddes, L A

    1990-03-01

    The series equivalent resistance R and capacitance C of metal/saline electrode/electrolyte interfaces were measured as a function of frequency (100 Hz-20k Hz) and current density (0.25 to 1000 A m-2) for eight typical electrode metals. For each of the metals tested, R decreased and C increased as the current density was increased above a critical value (with the exception of silver and MP35N at frequencies above 1 kHz for which R increased and C decreased slightly). With the exception of copper, the current density linearity limit (for 10 per cent decrease in R or 10 per cent increase in C) increased with increasing frequency and, in most cases, the current density linearity limit for 10 per cent increase in C was slightly less than that for 10 per cent decrease in R. Among the metals tested, copper and aluminium had the lowest current carrying capability and rhodium had the highest current-carrying capability. The current carrying capabilities of 316 SS, platinum, silver and MP35N, were intermediate and similar. With increasing current density, an increase in the electrode/electrolyte capacitance was the most sensitive indicator of the current-carrying linearity limit. PMID:2376994

  20. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

    PubMed Central

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-01-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration. PMID:27465437

  1. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles.

    PubMed

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-01-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration. PMID:27465437

  2. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

    NASA Astrophysics Data System (ADS)

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-07-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration.

  3. Fabrication and testing of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Klein, M. G.

    1978-01-01

    The development and life testing of single electrode and multi electrode stacks to optimize the individual components and characterize the performance of a silver hydrogen battery system are described. A NASA-developed inorganic separator material was used as the main separator within the cells. Single electrode test cells were cycled at 75% of nominal capacity out through approximately 1,000 cycles in a number of cases where deterioration in performance was observed. This deterioration appears to be a decay in usable capacity of the silver electrode; but the exact mechanism is still unidentified. Twenty ampere-hour boilerplate test cells consisting of a stack of ten silver electrodes and twenty hydrogen electrodes were cycled also at 75% depth of discharge. The oldest stack achieved 522 stable cycles to the end of the program. Weight analysis of light-weight cells showed that 50 ampere-hour cells with improved components could be capable of as much as 40 watt hours per pound.

  4. Non-gassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    The concept of a negative limited nongassing nickel-cadmium battery was demonstrated by constructing and testing practical size experimental cells of approximately 25 Ah capacity. These batteries operated in a gas-free manner and had measured energy densities of 10-11 Wh/lb. Thirty cells were constructed for extensive testing. Some small cells were tested for over 200 cycles at 100% depth. For example, a small cell with an electrodeposited cadmium active mass on a silver screen still had 55% of its theoretical capacity (initial efficiency was 85%). There was no evidence of deterioration of gassing properties with cycling of the nickel electrodes. The charge temperature was observed to be the most critical variable governing nickel electrode gassing. This variable was shown to be age dependent. Four types of cadmium electrodes were tested: an electrodeposited cadmium active mass on a cadmium or silver substrate, a porous sintered silver substrate based electrode, and a Teflon bonded pressed cadmium electrode. The electrodeposited cadmium mass on a silver screen was found to be the best all-around electrode from a performance point of view and from the point of view of manufacturing them in a size required for a 25 Ah size battery.

  5. Flexible carbon nanotubes electrode for neural recording.

    PubMed

    Lin, Chia-Min; Lee, Yu-Tao; Yeh, Shih-Rung; Fang, Weileun

    2009-05-15

    This paper demonstrates a novel flexible carbon nanotubes (CNTs) electrode array for neural recording. In this device, the CNTs electrode arrays are partially embedded into the flexible Parylene-C film using a batch microfabrication process. Through this fabrication process, the CNTs can be exposed to increase the total sensing area of an electrode. Thus, the flexible CNTs electrode of low impedance is realized. In application, the flexible CNTs electrode has been employed to record the neural signal of a crayfish nerve cord for in vitro recording. The measurements demonstrate the superior performance of the presented flexible CNTs electrode with low impedance (11.07 kohms at 1 kHz) and high peak-to-peak amplitude action potential (about 410 microV). In addition, the signal-to-noise ratio (SNR) of the presented flexible CNTs electrode is about 257, whereas the SNR of the reference (a pair of Teflon-coated silver wires) is only 79. The simultaneous recording of the flexible CNTs electrode array is also demonstrated. Moreover, the flexible CNTs electrode has been employed to successfully record the spontaneous spikes from the crayfish nerve cord. The amplitude of the spontaneous peak-to-peak response is about 25 microV. PMID:19272765

  6. Organic electrode coatings for next-generation neural interfaces.

    PubMed

    Aregueta-Robles, Ulises A; Woolley, Andrew J; Poole-Warren, Laura A; Lovell, Nigel H; Green, Rylie A

    2014-01-01

    Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes. PMID:24904405

  7. Organic electrode coatings for next-generation neural interfaces

    PubMed Central

    Aregueta-Robles, Ulises A.; Woolley, Andrew J.; Poole-Warren, Laura A.; Lovell, Nigel H.; Green, Rylie A.

    2014-01-01

    Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes. PMID:24904405

  8. CTAB-Influenced Electrochemical Dissolution of Silver Dendrites.

    PubMed

    O'Regan, Colm; Zhu, Xi; Zhong, Jun; Anand, Utkarsh; Lu, Jingyu; Su, Haibin; Mirsaidov, Utkur

    2016-04-19

    Dendrite formation on the electrodes of a rechargeable battery during the charge-discharge cycle limits its capacity and application due to short-circuits and potential ignition. However, understanding of the underlying dendrite growth and dissolution mechanisms is limited. Here, the electrochemical growth and dissolution of silver dendrites on platinum electrodes immersed in an aqueous silver nitrate (AgNO3) electrolyte solution was investigated using in situ liquid-cell transmission electron microscopy (TEM). The dissolution of Ag dendrites in an AgNO3 solution with added cetyltrimethylammonium bromide (CTAB) surfactant was compared to the dissolution of Ag dendrites in a pure aqueous AgNO3 solution. Significantly, when CTAB was added, dendrite dissolution proceeded in a step-by-step manner, resulting in nanoparticle formation and transient microgrowth stages due to Ostwald ripening. This resulted in complete dissolution of dendrites and "cleaning" of the cell of any silver metal. This is critical for practical battery applications because "dead" lithium is known to cause short circuits and high-discharge rates. In contrast to this, in a pure aqueous AgNO3 solution, without surfactant, dendrites dissolved incompletely back into solution, leaving behind minute traces of disconnected silver particles. Finally, a mechanism for the CTAB-influenced dissolution of silver dendrites was proposed based on electrical field dependent binding energy of CTA(+) to silver. PMID:27017834

  9. Effects of Kinetic Roughening and Liquid-Liquid Phase Transition on Lysozyme Crystal Growth Velocities

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar; Konnert, John; Forsythe, Elizabeth L.; Pusey, Marc L.

    2004-01-01

    We measured the growth velocities of the (110) face of tetragonal lysozyme, V (centimeters per second), at four different concentrations, c (milligrams per milliliter), as the solution temperature, T (Centigrade), was reduced. For a broad range of T dependent on c, we find that the growth velocities increased as the solution temperature was reduced. The initial increase in V is well characterized by the 2D nucleation model for crystal growth, yielding the magnitude of an effective barrier for growth, gamma(sub s) = 1.2 plus or minus 0.1 x 10(exp -13) erg/molecule. Below certain temperatures, T(sub cr), dependent on c, however, a kinetic roughening hypothesis that considers the continuous addition of molecules anywhere on the crystal surface better describes the observed growth velocities. The application of the continuous growth model, up to the solution cloud-point temperatures, T(sub cl), enabled the determinations of the crossover concentration, c(sub r), from estimated values of T(sub cr). For all conditions presented, we find that the crossover from growth by 2D nucleation to continuous addition occurs at a supersaturation, sigma (sub c), = 2.0 plus or minus 0.1. Moreover, we find the energy barrier for the continuous addition, E(sub c), within the temperature range T(sub cl) less than T less than T less than T (sub cr), to be 6 plus or minus 1 x 10(exp -13) erg/molecule. Further reduction of T below approximately 2-3 C of T(sub cl), also revealed a rapid slowing of crystal growth velocities. From quasi-elastic light scattering investigations, we find that the rapid diminishment of crystal growth velocities can be accounted for by the phase behavior of lysozyme solutions. Namely, we find the reversible formation of dense fluid proto-droplets comprised of lysozyme molecules to occur below approximately 0.3 C of T(sub cl). Hence, the rapid slowing of growth velocities may occur as a result of the sudden depletion of "mobile" molecules within crystal growth

  10. Silver(I) ion-selective membrane based on Schiff base-p-tert-butylcalix[4]arene.

    PubMed

    Mahajan, R K; Kumar, M; Sharma, V; Kaur, I

    2001-04-01

    A PVC membrane electrode for silver(I) ion based on Schiff base-p-tert-butylcalix[4]arene is reported. The electrode works well over a wide range of concentration (1.0 x 10(-5)-1.0 x 10(-1) mol dm-3) with a Nernstian slope of 59.7 mV per decade. The electrode shows a fast response time of 20 s and operates in the pH range 1.0-5.6. The sensor can be used for more than 6 months without any divergence in the potential. The selectivity of the electrode was studied and it was found that the electrode exhibits good selectivity for silver ion over some alkali, alkaline earth and transition metal ions. The silver ion-selective electrode was used as an indicator electrode for the potentiometric titration of silver ion in solution using a standard solution of sodium chloride; a sharp potential change occurs at the end-point. The applicability of the sensor to silver(I) ion measurement in water samples spiked with silver nitrate is illustrated. PMID:11340988

  11. Silver and Gold NMR

    PubMed Central

    Zangger, Klaus

    1999-01-01

    Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope (197Au), which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms (109Ag and 109Au), both of which have a spin 1/2 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on 109Ag. PMID:18475898

  12. Genetics Home Reference: Silver syndrome

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions Silver syndrome Silver syndrome Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Silver syndrome belongs to a group of genetic disorders ...

  13. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

    The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

  14. Cermet electrode

    DOEpatents

    Maskalick, Nicholas J.

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  15. Magnetohydrodynamic electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.

    1978-01-01

    An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

  16. Surface-Plasmon Enhanced Transparent Electrodes in Organic Photovoltaics

    SciTech Connect

    Reilly III, T. H.; van de Lagemaat, J.; Tenent, R. C.; Morfa, A. J.; Rowlen, K. L.

    2008-01-01

    Random silver nanohole films were created through colloidal lithography techniques and metal vapor deposition. The transparent electrodes were characterized by uv-visible spectroscopy and incorporated into an organic solar cell. The test cells were evaluated for solar power-conversion efficiency and incident photon-to-current conversion efficiency. The incident photon-to-current conversion efficiency spectra displayed evidence that a nanohole film with 92 nm diameter holes induces surface-plasmon-enhanced photoconversion. The nanohole silver films demonstrate a promising route to removing the indium tin oxide transparent electrode that is ubiquitous in organic optoelectronics.

  17. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (Inventor)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  18. Successively thresholded domain boundary roughening driven by pinning centers and missing bonds: Hard-spin mean-field theory applied to d=3 Ising magnets.

    PubMed

    Çağlar, Tolga; Berker, A Nihat

    2015-12-01

    Hard-spin mean-field theory has recently been applied to Ising magnets, correctly yielding the absence and presence of an interface roughening transition respectively in d=2 and d=3 dimensions and producing the ordering-roughening phase diagram for isotropic and anisotropic systems. The approach has now been extended to the effects of quenched random pinning centers and missing bonds on the interface of isotropic and anisotropic Ising models in d=3. We find that these frozen impurities cause domain boundary roughening that exhibits consecutive thresholding transitions as a function of interaction anisotropy. For both missing-bond and pinning-center impurities, for moderately large values of the anisotropy, the systems saturate to the "solid-on-solid" limit, exhibiting a single universal curve for the domain boundary width as a function of impurity concentration. PMID:26764656

  19. Hybrid surface roughening modes during low-temperature heteroepitaxy: Growth of fully-strained metastable Ge1-xSnx alloys on Ge(001)2×1

    NASA Astrophysics Data System (ADS)

    Desjardins, P.; Spila, T.; Gürdal, O.; Taylor, N.; Greene, J. E.

    1999-12-01

    Fully-strained single-crystal metastable Ge1-xSnx alloys were grown on Ge(001) up to their critical epitaxial thickness values tepi(x) in order to probe surface roughening pathways leading to heteroepitaxial breakdown during low-temperature molecular-beam epitaxy under large compressive strain. All films with x>0.09 have comparable roughnesses while films with x<0.09 are considerably rougher with larger lateral feature sizes. Roughening rates increase with increasing x for films with x>0.09 due to a new hybrid relaxation path which only becomes accessible under high strain as kinetic roughening provides surface oscillations on lateral length scales that allow bulk relaxation through strain-induced islanding at growth temperatures where it could not otherwise proceed.

  20. The fate of nano-silver in aqueous media

    NASA Astrophysics Data System (ADS)

    Plowman, Blake. J.; Tschulik, Kristina; Walport, Emily; Young, Neil P.; Compton, Richard G.

    2015-07-01

    Silver nanoparticles offer highly attractive properties for many applications, however concern has been raised over the possible toxicity of this material in environmental systems. While it is thought that the release of Ag+ can play a crucial role in this toxicity, the mechanism by which the oxidative dissolution of nano-silver occurs is not yet understood. Here we address this through the electrochemical analysis of gold-core silver-shell nanoparticles in various solutions. This novel method allows the direct quantification of silver dissolution by normalisation to the gold core signal. This is shown to be highly effective at discriminating between silver dissolution and the loss of nanoparticles from the electrode surface. We evidence through this rigorous approach that the reduction of O2 drives the dissolution of nano-silver, while in the presence of Cl- this dissolution is greatly inhibited. This work is extended to the single nanoparticle level using nano-impact experiments.Silver nanoparticles offer highly attractive properties for many applications, however concern has been raised over the possible toxicity of this material in environmental systems. While it is thought that the release of Ag+ can play a crucial role in this toxicity, the mechanism by which the oxidative dissolution of nano-silver occurs is not yet understood. Here we address this through the electrochemical analysis of gold-core silver-shell nanoparticles in various solutions. This novel method allows the direct quantification of silver dissolution by normalisation to the gold core signal. This is shown to be highly effective at discriminating between silver dissolution and the loss of nanoparticles from the electrode surface. We evidence through this rigorous approach that the reduction of O2 drives the dissolution of nano-silver, while in the presence of Cl- this dissolution is greatly inhibited. This work is extended to the single nanoparticle level using nano-impact experiments

  1. Surface roughening of silicon, thermal silicon dioxide, and low-k dielectric coral films in argon plasma

    SciTech Connect

    Yin Yunpeng; Sawin, Herbert H.

    2008-01-15

    The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followed the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.

  2. A super ink jet printed zinc-silver 3D microbattery

    NASA Astrophysics Data System (ADS)

    Ho, C. C.; Murata, K.; Steingart, D. A.; Evans, J. W.; Wright, P. K.

    2009-09-01

    A novel super ink jet printing (SIJP) system was used to fabricate 3D zinc-silver microbatteries directly on a substrate. The SIJP provides a simple and flexible method to deposit interesting 2D and 3D structures of varying morphologies without the waste and large energy inputs typical of standard microfabrication technologies. The system was used to print pairs of silver electrodes with arrays of pillars on glass substrates, and in the presence of an electrolyte, the battery self-assembled during the first charge. Using an aqueous electrolyte solution of KOH with dissolved ZnO, the SIJP printed structures showed similar electrochemical behavior to batteries composed of silver foil electrodes. For a sparse array of pillars (~2.5% footprint area of each electrode pad occupied by pillars), a capacity increase of 60% was achieved in comparison with a cell with planar electrodes.

  3. Transparent metal electrodes from ordered nanosphere arrays

    NASA Astrophysics Data System (ADS)

    Morfa, Anthony J.; Akinoglu, Eser M.; Subbiah, Jegadesan; Giersig, Michael; Mulvaney, Paul

    2013-08-01

    We show that perforated metal electrode arrays, fabricated using nanosphere lithography, provide a viable alternative to conductive metal oxides as transparent electrode materials. The inter-aperture spacing is tuned by varying etching times in an oxygen plasma, and the effect of inter-aperture "wire" thickness on the optical and electronic properties of perforated silver films is shown. Optical transmission is limited by reflection and surface plasmons, and for these results do not exceed 73%. Electrical sheet resistance is shown to be as low as 3 Ω ◻-1 for thermally evaporated silver films. The performance of organic photovoltaic devices comprised of a P3HT:PCBM bulk heterojunction deposited onto perforated metal arrays is shown to be limited by optical transmission, and a simple model is presented to overcome these limitations.

  4. Long term investigations of silver cathodes for alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Wagner, N.; Schulze, M.; Gülzow, E.

    Alkaline fuel cells (AFC) are an interesting alternative to polymer electrolyte fuel cells (PEFC). In AFC no expensive platinum metal is necessary; silver can be used for the oxygen reduction reaction (ORR) (cathode catalyst). For technical use of AFC the long term behavior of AFC components is important, especially that of the electrodes. The investigated cathodes for AFC consist of a mixture of silver catalyst and polytetrafluorethylene (PTFE) as organic binder rolled onto a metal web. The electrodes were electrochemically investigated through measuring V- i curves and electrochemical impedance spectroscopy (EIS). The electrochemical characterization and the long term tests were performed in half-cells at 70 °C using pure oxygen (1 bar) under galvanostatic conditions. The cathodes were electrochemically investigated in half-cells using reference electrodes (Hg/HgO) by periodically recording V- i curve and electrochemical impedance spectroscopy. In addition, the cathodes were physically characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).

  5. The silver ions contribution into the cytotoxic activity of silver and silver halides nanoparticles

    NASA Astrophysics Data System (ADS)

    Klimov, A. I.; Zherebin, P. M.; Gusev, A. A.; Kudrinskiy, A. A.; Krutyakov, Y. A.

    2015-11-01

    The biocidal action of silver nanoparticles capped with sodium citrate and silver halides nanoparticles capped with non-ionic surfactant polyoxyethylene(20)sorbitan monooleate (Tween 80®) against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells. The cytotoxicity of the obtained colloids was strongly correlated with silver ion content in the dispersions. The results clearly indicated that silver and silver halides nanoparticles destroyed yeast cells through the intermediate producing of silver ions either by dissolving of salts or by oxidation of silver.

  6. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

    Many colleges address complex problems with a single "silver bullet" strategy. Because value shifts according to the consumer's situation or goal, private colleges should become more aware of their "situational value" and exploit it. This requires an understanding of how students choose colleges. In contrast, popular silver bullets target…

  7. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  8. Method for the recovery of silver from silver zeolite

    SciTech Connect

    Reimann, George A.

    1986-01-01

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  9. Laser patterning of platinum electrodes for safe neurostimulation

    NASA Astrophysics Data System (ADS)

    Green, R. A.; Matteucci, P. B.; Dodds, C. W. D.; Palmer, J.; Dueck, W. F.; Hassarati, R. T.; Byrnes-Preston, P. J.; Lovell, N. H.; Suaning, G. J.

    2014-10-01

    Objective. Laser surface modification of platinum (Pt) electrodes was investigated for use in neuroprosthetics. Surface modification was applied to increase the surface area of the electrode and improve its ability to transfer charge within safe electrochemical stimulation limits. Approach. Electrode arrays were laser micromachined to produce Pt electrodes with smooth surfaces, which were then modified with four laser patterning techniques to produce surface structures which were nanosecond patterned, square profile, triangular profile and roughened on the micron scale through structured laser interference patterning (SLIP). Improvements in charge transfer were shown through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and biphasic stimulation at clinically relevant levels. A new method was investigated and validated which enabled the assessment of in vivo electrochemically safe charge injection limits. Main results. All of the modified surfaces provided electrical advantage over the smooth Pt. The SLIP surface provided the greatest benefit both in vitro and in vivo, and this surface was the only type which had injection limits above the threshold for neural stimulation, at a level shown to produce a response in the feline visual cortex when using an electrode array implanted in the suprachoroidal space of the eye. This surface was found to be stable when stimulated with more than 150 million clinically relevant pulses in physiological saline. Significance. Critical to the assessment of implant devices is accurate determination of safe usage limits in an in vivo environment. Laser patterning, in particular SLIP, is a superior technique for improving the performance of implant electrodes without altering the interfacial electrode chemistry through coating. Future work will require chronic in vivo assessment of these electrode patterns.

  10. Silver nanostructures synthesis via optically induced electrochemical deposition

    PubMed Central

    Li, Pan; Liu, Na; Yu, Haibo; Wang, Feifei; Liu, Lianqing; Lee, Gwo-Bin; Wang, Yuechao; Li, Wen Jung

    2016-01-01

    We present a new digitally controlled, optically induced electrochemical deposition (OED) method for fabricating silver nanostructures. Projected light patterns were used to induce an electrochemical reaction in a specialized sandwich-like microfluidic device composed of one indium tin oxide (ITO) glass electrode and an optically sensitive-layer-covered ITO electrode. Silver polyhedral nanoparticles, triangular and hexagonal nanoplates, and nanobelts were controllably synthesized in specific positions at which projected light was illuminated. The silver nanobelts had rectangular cross-sections with an average width of 300 nm and an average thickness of 100 nm. By controlling the applied voltage, frequency, and time, different silver nanostructure morphologies were obtained. Based on the classic electric double-layer theory, a dynamic process of reduction and crystallization can be described in terms of three phases. Because it is template- and surfactant-free, the digitally controlled OED method facilitates the easy, low cost, efficient, and flexible synthesis of functional silver nanostructures, especially quasi-one-dimensional nanobelts. PMID:27295084

  11. Silver nanostructures synthesis via optically induced electrochemical deposition.

    PubMed

    Li, Pan; Liu, Na; Yu, Haibo; Wang, Feifei; Liu, Lianqing; Lee, Gwo-Bin; Wang, Yuechao; Li, Wen Jung

    2016-01-01

    We present a new digitally controlled, optically induced electrochemical deposition (OED) method for fabricating silver nanostructures. Projected light patterns were used to induce an electrochemical reaction in a specialized sandwich-like microfluidic device composed of one indium tin oxide (ITO) glass electrode and an optically sensitive-layer-covered ITO electrode. Silver polyhedral nanoparticles, triangular and hexagonal nanoplates, and nanobelts were controllably synthesized in specific positions at which projected light was illuminated. The silver nanobelts had rectangular cross-sections with an average width of 300 nm and an average thickness of 100 nm. By controlling the applied voltage, frequency, and time, different silver nanostructure morphologies were obtained. Based on the classic electric double-layer theory, a dynamic process of reduction and crystallization can be described in terms of three phases. Because it is template- and surfactant-free, the digitally controlled OED method facilitates the easy, low cost, efficient, and flexible synthesis of functional silver nanostructures, especially quasi-one-dimensional nanobelts. PMID:27295084

  12. Silver nanostructures synthesis via optically induced electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Li, Pan; Liu, Na; Yu, Haibo; Wang, Feifei; Liu, Lianqing; Lee, Gwo-Bin; Wang, Yuechao; Li, Wen Jung

    2016-06-01

    We present a new digitally controlled, optically induced electrochemical deposition (OED) method for fabricating silver nanostructures. Projected light patterns were used to induce an electrochemical reaction in a specialized sandwich-like microfluidic device composed of one indium tin oxide (ITO) glass electrode and an optically sensitive-layer-covered ITO electrode. Silver polyhedral nanoparticles, triangular and hexagonal nanoplates, and nanobelts were controllably synthesized in specific positions at which projected light was illuminated. The silver nanobelts had rectangular cross-sections with an average width of 300 nm and an average thickness of 100 nm. By controlling the applied voltage, frequency, and time, different silver nanostructure morphologies were obtained. Based on the classic electric double-layer theory, a dynamic process of reduction and crystallization can be described in terms of three phases. Because it is template- and surfactant-free, the digitally controlled OED method facilitates the easy, low cost, efficient, and flexible synthesis of functional silver nanostructures, especially quasi-one-dimensional nanobelts.

  13. Silver(II) Oxide or Silver(I,III) Oxide?

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

    The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

  14. Mineral commodity profiles: Silver

    USGS Publications Warehouse

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  15. Microwave dielectric properties and chemical compatibility with silver electrode of Li2TiO3 ceramic with Li2O-ZnO-B2O3 glass additive

    NASA Astrophysics Data System (ADS)

    Sayyadi-Shahraki, A.; Taheri-Nassaj, E.; Hassanzadeh-Tabrizi, S. A.; Barzegar-Bafrooei, H.

    2015-01-01

    The effects of Li2O-ZnO-B2O3 (LZB) glass additive on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Li2TiO3 (LT) ceramics have been investigated. The addition of a small amount of LZB glass can reduce the sintering temperature of LT ceramics from 1150 °C to 900 °C without obvious degradation of the microwave dielectric properties. Only a single-phase Li2TiO3 is formed in LT ceramic with LZB glass addition sintered at 900 °C for 2 h. Typically, the 2.5 wt% LZB glass-added LT ceramic sintered at 900 °C for 2 h can reach a maximum relative density of 94.8% of the theoretical density and exhibits good microwave dielectric properties of εr=22.9, Qf=59,600 GHz and τf=+23.7 ppm/°C. The XRD, SEM and EDX analyses showed that the ceramic can be co-fired well with Ag electrode, which may be applied for LTCC application.

  16. Phagocytic and metabolic reactions to chronically implanted metal brain electrodes.

    PubMed

    Babb, T L; Kupfer, W

    1984-11-01

    In order to study the biocompatibility of metal electrodes and insulations in the rat brain, eight different metal electrode types and two different insulations were implanted for 11, 35, 36, 37, or 63 days. Stainless steel and Nichrome were nontoxic metals, silver was toxic, and copper extremely toxic with phagocytosis active to 37 days of implantation. Active phagocytosis was easily detected by high glucose demand using 2-deoxy[14C]glucose (2-DG) autoradiography contrasted with normal 2-DG autoradiographs where phagocytes were present but not ingesting. Epoxylite, an epoxy-polyester varnish, was slightly more reactive in brain than polyimide but not statistically significant. In general, larger electrodes created more tissue reaction per se for as long as 37 days. These results suggested that a thin stainless-steel bipolar electrode will provide safe recording electrodes in either animal or human brain. The importance of these findings is that certain metals (silver, copper) cannot be used in the brain without producing necrosis and phagocytosis, whereas other metals (stainless steel, Nichrome) with varnish insulators (Epoxylite, polyimide) can be implanted without producing any detectable damage beyond that of the initial trauma and brief phagocytosis limited to the edge of the electrode track. Finally, the glucose metabolism autoradiographs differentiated active phagocytosis (copper) from inactive phagocytes (silver) when using long implants (37 days) of toxic metals. PMID:6489492

  17. Study of roughness-induced diffuse and specular reflectance at silver-air and silver-liquid interfaces. Final report, July 1, 1979-August 31, 1980

    SciTech Connect

    Sari, S.O.

    1980-07-01

    Results of an extended investigation of surface plasma-wave absorption and roughness-induced optical scattering from an interface of silver and air are described. In particular, the position of the surface plasma resonance minimum in reflectivity for a stochastically roughened metal silver surface has been studied as a function of a number of distinct roughness perturbations. In the case of a transparent liquid-silver boundary the frequency red shift of the resonance minimum has been determined and the location of the surface plasmon dip for various liquids is shown to agree well with a simple roughness theory. The additional interfacial properties due to the formation of a thin inhomogeneous oxide layer occurring either spontaneously or due to application of a small interfacial electrical potential are more complex. However, the optical constants of the interlayer have been determined from differential specular reflectance measurements at the boundary. Nodule size parameters determined from scattering and absorption measurements and features of both polarized and depolarized diffuse reflectance give further information on the state of the interface. Reflectance of ordered-corrugated surfaces are also described.

  18. Roll-to-roll printed silver nanowires for increased stability of flexible ITO-free organic solar cell modules

    NASA Astrophysics Data System (ADS)

    Dos Reis Benatto, Gisele A.; Roth, Bérenger; Corazza, Michael; Søndergaard, Roar R.; Gevorgyan, Suren A.; Jørgensen, Mikkel; Krebs, Frederik C.

    2015-12-01

    We report the use of roll-to-roll printed silver nanowire networks as front electrodes for fully roll-to-roll processed flexible indium-tin-oxide (ITO) free OPV modules. We prepared devices with two types of back electrodes, a simple PEDOT:PSS back electrode and a PEDOT:PSS back electrode with a printed silver grid in order to simultaneously explore the influence of the back electrode structure on the operational stability of the modules that did not include any UV-protection. We subjected the devices to stability testing under a number of protocols recommended by the international summit on OPV stability (ISOS). We explored accelerated ISOS-D-2, ISOS-D-3, ISOS-L-2, ISOS-L-3, ISOS-O-1 and ISOS-O-2 testing protocols and compared the performance to previous reports employing the same testing protocols on devices with PEDOT:PSS instead of the silver nanowires in the front electrode. We find significantly increased operational stability across all ISOS testing protocols over the course of the study and conclude that replacement of PEDOT:PSS in the front electrode with silver nanowires increase operational stability by up to 1000%. The duration of the tests were in the range of 140-360 days. The comparison of front and back electrode stability in this study shows that the modules with silver nanowire front electrodes together with a composite back electrode comprising PEDOT:PSS and a silver grid present the best operational stability.

  19. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed. PMID:27472594

  20. Impact of etching kinetics on the roughening of thermal SiO{sub 2} and low-k dielectric coral films in fluorocarbon plasmas

    SciTech Connect

    Yin Yunpeng; Sawin, Herbert H.

    2007-07-15

    The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ion scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.

  1. The development of a micropatterned electrode for studies of zinc electrodeposition

    SciTech Connect

    Sutija, D.P.; Muller, R.H.; Tobias, C.W.

    1986-12-01

    A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.

  2. Fabrication of interdigitated electrodes by inkjet printing technology for apllication in ammonia sensing

    NASA Astrophysics Data System (ADS)

    Dam Le, Duy; Nhien Nguyen, Thi Ngoc; Chanh Tin Doan, Duc; Dung Dang, Thi My; Chien Dang, Mau

    2016-06-01

    In this paper interdigitated electrodes for gas sensors were fabricated by inkjet printing technology. Silver electrodes were inkjet printed on Si/SiO2 substrates instead of traditional photolithography method. The inkjet printing parameters to obtain desired dimensions, thickness of the electrodes and distance between the interdigitated electrodes were optimized in this study. The fabricated interdigitated silver electrodes were tested for application in ammonia gas sensors. Conductive polyaniline (PANI) layer was coated on the silver interdigitated electrodes by drop-coating. Ammonia detection of the PANI-coated chips was characterized with a gas measurement system in which humidity and ammonia concentrations were well-controlled. The electrical conductivity of the PANI films coated on the electrodes was measured when the PANI films were exposed to nitrogen and ammonia. The conductivity of the PANI films decreased significantly due to the deprotonation process of PANI upon ammonia expodure. The recovery time was about 15 min by heating up the polymer chip at 60 °C. The results showed that the silver electrodes fabricated by inkjet printing technique could be used as a sensor platform for ammonia detection.

  3. Divalent silver oxide cell containing cadmium and tellurium components

    SciTech Connect

    Ohya, Y.; Shimizu, T.

    1982-07-06

    A divalent silver oxide cell of the type having a positive electrode formed mainly of divalent silver oxide has its stability greatly improved by adding a cadmium component and a tellurium component and, optionally, at least one auxiliary component containing an element selected from the group consisting of thallium, mercury, lead, germanium, yttrium, tin, tungsten, lanthanum, rare earth elements, zinc, aluminum and selenium, each to either the divalent silver oxide, the alkaline electrolyte, or both. The cadmium component is contained in a concentration of not less than 0.03% by weight when in the divalent silver oxide and not less than 0.01 g/liter when in the alkaline electrolyte; and tellurium component in a concentration of not less than 0.01% by weight when in the divalent silver oxide and not less than 0.01 g/liter when in the alkaline electrolyte; and the at least one auxiliary component in a total concentration of not less than 0.01% by weight when in the divalent silver oxide and not less than 0.01 g/liter when in the alkaline electrolyte.

  4. Thin metal layer as transparent electrode in n-i-p amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Theuring, Martin; Geissendörfer, Stefan; Vehse, Martin; von Maydell, Karsten; Agert, Carsten

    2014-07-01

    In this paper, transparent electrodes, based on a thin silver film and a capping layer, are investigated. Low deposition temperature, flexibility and low material costs are the advantages of this type of electrode. Their applicability in structured n-i-p amorphous silicon solar cells is demonstrated in simulation and experiment. The influence of the individual layer thicknesses on the solar cell performance is discussed and approaches for further improvements are given. For the silver film/capping layer electrode, a higher solar cell efficiency could be achieved compared to a reference ZnO:Al front contact.

  5. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  6. Synthesis and applications of novel silver nanoparticle structures

    NASA Astrophysics Data System (ADS)

    Dukes, Kyle

    template base self assembly. A 1.5 micron silica sphere is bound to poly(4-vinylpyridine) coated glass and used as a template. a mask of silica monoxide is vacuum deposited atop the spheres/glass leaving a ring just below the sphere untouched and able to bind silver nanoparticles. Optical microscopy reveal interesting results under depolarized light conditions, but ultimate structural analysis has proven elusive. Semiconducting p-type cuprous oxide was electrochemically deposited on both silver and indium tin oxide electrodes. Silver nanoparticles were incorporated into the architecture either atop the cuprous oxide or sandwiched between cuprous oxide and n-type material. Increases in photocurrent were observed in both cases and further work must be conducted to optimize a solid state device for photovoltaic applications.

  7. Activity coefficients of aqueous sodium chloride from 15° to 50°C measured with a glass electrode

    USGS Publications Warehouse

    Truesdell, A.H.

    1968-01-01

    Values of the mean activity coefficient of sodium chloride at 15°, 25°, 38° and 50°C were determined for aqueous NaCl solutions of 0.01 to 1.0 molal from electromotive force measurements on the cell: (sodium-sensitive glass electrode, aqueous sodium chloride, silver chloride-silver).

  8. Contribution to the study of the electric arc: Erosion of metallic electrodes. Thesis

    NASA Technical Reports Server (NTRS)

    Castro, A.

    1986-01-01

    A procedure is described for determining the extent of arc electrode erosion (excluding erosion due to transfer of material) from measurements of emitted spectral beam intensity. The relation between emission intensity and plasma temperature is ascertained. Experimental study of several combinations of monometallic electrodes shows that the method is suitable for determining cathode erosion, although the anode metal affects the extent of erosion. Combinations of electrodes which lead to low erosion of silver are reported.

  9. Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes.

    PubMed

    Rich, Michelle; Mendecki, Lukasz; Mensah, Samantha T; Blanco-Martinez, Enrique; Armas, Stephanie; Calvo-Marzal, Percy; Radu, Aleksandar; Chumbimuni-Torres, Karin Y

    2016-09-01

    Preparation of ion-selective electrodes (ISEs) often requires long and complicated conditioning protocols limiting their application as tools for in-field measurements. Herein, we eliminated the need for electrode conditioning by loading the membrane cocktail directly with primary ion solution. This proof of concept experiment was performed with iodide, silver, and sodium selective electrodes. The proposed methodology significantly shortened the preparation time of ISEs, yielding functional electrodes with submicromolar detection limits. Moreover, it is anticipated that this approach may form the basis for the development of miniaturized all-solid-state ion-selective electrodes for in situ measurements. PMID:27523089

  10. Hybrid electrode based on carbon nanotube and graphene for ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Seo, Tae Hoon; Lee, Gun Hee; Park, Sungchan; Chandramohan, S.; Park, Ah Hyun; Cho, Hyunjin; Park, Min; Jong Kim, Myung; Suh, Eun-Kyung

    2015-10-01

    We report on a transparent current-spreading electrode that combines carbon nanotubes (CNTs) and graphene for UV-LEDs. We compared the device performance and long-term stability of this CNT-graphene hybrid electrode (CGE) with those of the silver nanowire-graphene electrode (SGE) reported previously. Both types of electrode offered excellent UV transmittance and reduced sheet resistance through the bridging effect for grain boundaries and defects in graphene by nanotubes or nanowires. UV-LEDs using such electrodes offered reduced forward voltage and enhanced electroluminescence intensity, but the device with the CGE showed excellent stability whereas the SGE degraded with time.

  11. Anodic Stripping Voltammetry of Silver Nanoparticles: Aggregation Leads to Incomplete Stripping

    PubMed Central

    Cloake, Samantha J; Toh, Her Shuang; Lee, Patricia T; Salter, Chris; Johnston, Colin; Compton, Richard G

    2015-01-01

    The influence of nanoparticle aggregation on anodic stripping voltammetry is reported. Dopamine-capped silver nanoparticles were chosen as a model system, and melamine was used to induce aggregation in the nanoparticles. Through the anodic stripping of the silver nanoparticles that were aggregated to different extents, it was found that the peak area of the oxidative signal corresponding to the stripping of silver to silver(I) ions decreases with increasing aggregation. Aggregation causes incomplete stripping of the silver nanoparticles. Two possible mechanisms of ‘partial oxidation’ and ‘inactivation’ of the nanoparticles are proposed to account for this finding. Aggregation effects must be considered when anodic stripping voltammetry is used for nanoparticle detection and quantification. Hence, drop casting, which is known to lead to aggregation, is not encouraged for preparing electrodes for analytical purposes. PMID:25861566

  12. Nickel hydrogen and silver zinc battery cell modeling at the Aerospace Corporation

    SciTech Connect

    Zimmerman, A.H.

    1996-02-01

    A nickel hydrogen battery cell model has been fully developed and implemented at The Aerospace Corporation. Applications of this model to industry needs for the design of better cells, power system design and charge control thermal management, and long-term performance trends will be described. Present efforts will be described that are introducing the silver and zinc electrode reactions into this model architecture, so that the model will be able to predict performance for not only silver zinc cells, but also nickel zinc, silver hydrogen, and silver cadmium cells. The silver zinc cell modeling effort is specifically designed to address the concerns that arise most often in launch vehicle applications: transient response, power-on voltage regulation, hot or cold operation, electrolyte spewing, gas venting, self-discharge, separator oxidation, and oxalate crystal growth. The specific model features that are being employed to address these issues will be described.

  13. sensor electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiqiang; Ma, Congcong; He, Lian; Zhu, Shijin; Hao, Xiaodong; Xie, Wanyi; Zhang, Wei; Zhang, Yuxin

    2014-11-01

    In this work, an ultrafast and facile method is developed to synthesize Au(I)-dodecanethiolate nanotubes (Au(I)NTs) with the assistance of glycyl-glycyl-glycine (G-G-G). Transmission electron microscopy (TEM) images reveal that the as-prepared Au(I)NTs can be obtained in a 2-h reaction instead of a previous 24-h reaction and are uniform with a hollow structure and smooth surface by virtue of the G-G-G peptide tubular template. According to structural analysis, a possible preparative mechanism is proposed that the G-G-G peptide could help to curl into tube-like morphology in alkaline situation spontaneously to accelerate the formation of Au(I)NTs. Meanwhile, PVDF-stabilized Au(I)NT-modified glassy carbon electrodes present their promising potential for Hg2+ detection.

  14. A long-lived external Ag/AgCl reference electrode for use in high temperature/pressure environments

    SciTech Connect

    Danielson, M.J.

    1983-05-01

    High temperature pressure Ag/AgCl electrodes resistant to the contaminating effects of H/sub 2/ and H/sub 2/S were described in 1979. But the external reference electrode suffers from a thermal liquid junction potential (TLJP) and the development of the Soret effect (thermo-diffusion of the electrolyte). This paper describes a design to improve electrode life. A silvered-tube replaces the silver wire electrode. A liquid chromatograph minipump is used to slowly inject KC1 solution into the electrode to maintain a ''front'' of fresh solution. This prevents ageing effects, and the Soret effect. Construction specifications are given for: corrosion resistant tubing, electrical gland end, zirconium yarn, titanium tubing, polyimide collar, PTFE tubing, minipumps for chromatograph, zirconia plug, and silver chloride.

  15. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  16. Novel flexible Dry multipin electrodes for EEG: Signal quality and interfacial impedance of Ti and TiN coatings.

    PubMed

    Fiedler, P; Fonseca, C; Pedrosa, P; Martins, A; Vaz, F; Griebel, S; Haueisen, J

    2013-01-01

    Conventional Silver/Silver-Chloride electrodes are inappropriate for routine high-density EEG and emerging new fields of application like brain computer interfaces. A novel multipin electrode design is proposed. It enables rapid and easy application while maintaining signal quality and patient comfort. The electrode design is described and impedance and EEG tests are performed with Titanium and Titanium Nitride coated electrodes. The results are compared to conventional reference electrodes in a multi-volunteer study. The calculated signal parameters prove the multipin electrode concept to reproducibly acquire EEG signal quality comparable to Ag/AgCl electrodes. The promising results encourage further investigation and can provide a technological base for future preparation-free multichannel EEG systems. PMID:24109745

  17. resterilizable electrode for electrosurgery

    NASA Technical Reports Server (NTRS)

    Engstrom, E. R.; Houge, J. C.

    1979-01-01

    Required properties of flexibility, electrical conductivity, tensile strength, and tear resistance of electrosurgical electrodes is retained through utilization of flexible-polymer/conductive particle composites for electrodes.

  18. Observation of water-shock-wave propagation emanated from the roughened optical fiber end surface by the pulse laser energy input

    NASA Astrophysics Data System (ADS)

    Nakahara, Motonao; Nagayama, Kunihito

    1999-06-01

    Pressure enhancement of the generated shock waves in water has been found, when pulse laser energy is transmitted through an optical fiber whose end surface is intentionally roughened. More effective high-pressure shock generation can be possible by the aluminum coating on the roughened fiber surface. In case of the moderate laser energy of about 50 mJ input to the fiber, it is found that the phenomena are dependent on (1) the roughness, (2) the fiber diameter, and (3) the ambient medium. Shock wave generation can be detected successively by the laser input, but found to degrade down. Cavitation bubbles have also been observed after each shot. When the fiber end is in air, an intense and long-stretched flash can be observed. We have observed the phenomena by the pulse laser shadowgraphy.

  19. Improved luminance intensity of InGaN-GaN light-emitting diode by roughening both the p-GaN surface and the undoped-GaN surface

    NASA Astrophysics Data System (ADS)

    Peng, Wei Chih; Wu, Yew Chung Sermon

    2006-07-01

    The InGaN-GaN epitaxial films were grown by low-pressure metal-organic chemical vapor deposition on a sapphire substrate, and then the light-emitting diode (LED) with double roughened (p-GaN and undoped-GaN) surfaces was fabricated by surface-roughening, wafer-bonding, and laser lift-off technologies. It was found that the front side luminance intensity of double roughened LED was 2.77 times higher than that of the conventional LED at an injection current of 20mA. The backside luminance intensity was 2.37 times higher than that of the conventional LED. This is because the double roughened surfaces can provide photons multiple chances to escape from the LED surface, and redirect photons, which were originally emitted out of the escape cone, back into the escape cone.

  20. Effect of surface roughening on the catalytic activity of Pt-Cr electrocatalysts for the oxygen reduction in phosphoric acid fuel cell

    SciTech Connect

    Kim, K.T.; Kim, Y.G.; Chung, J.S.

    1995-05-01

    A Pt-Cr bimetallic catalyst with an atomic ratio of 3 to 1 was prepared by the impregnation method using a Pt/C catalyst (Pt loading: 10 weight percent). The catalyst was subjected to heat-treatment from 400 to 1,200 C. Its physical properties were characterized by H{sub 2}-O{sub 2} chemisorption, X-ray diffraction, transmission electron microscopy, and energy dispersive spectroscopy. Changes in the catalytic activity for oxygen reduction in PAFC were also examined. In particular, surface roughening caused by acid pretreatment and/or potential excursion was investigated to see its effect on the activity. Acid treatment (in 1M H{sub 2}SO{sub 4} for 1 day) and/or potential excursion at a mild condition (with a limited upper potential of 0.9 V vs. RHE) effectively created surface roughening without showing particle growth via sintering. The surface roughening increased the Pt surface area and consequently mass activity (catalytic activity based on mass of Pt) of the catalysts due to the selective leaching of surface-enriched chromium species. Concerning the specific activity (catalytic activity based on the Pt surface area), Pt-Cr having a smaller lattice parameter than Pt-Fe or Pt showed better performance, and this rule could be extended for other alloy systems. The mass activity, which is more important for practical applications, could be enhanced substantially when the surface roughening was brought on the catalyst surface while keeping the metal particle size small. The largest enhancement in the mass activity was observed when a partially alloyed or disordered alloy of Pt-Cr catalyst was subjected to the acid treatment or to the potential excursion.

  1. Effect of curing temperature on nano-silver paste ink for organic thin-film transistors.

    PubMed

    Kim, Minseok; Koo, Jae Bon; Baeg, Kang-Jun; Noh, Yong-Young; Yang, Yong Suk; Jung, Soon-Won; Ju, Byeong-Kwon; You, In-Kyu

    2012-04-01

    Silver (Ag) metal electrode having 20 microm channel length was printed by reverse offset printing (ROP) using nano-silver paste ink for the source/drain of organic thin-film transistors (OTFT). Specific resistance and surface roughness of printed Ag electrodes with increasing curing temperature were investigated, and surface morphology and grain growth mechanism were systematically verified using a scanning electron microscope (SEM) and atomic force microscope (AFM) in order to obtain an optimized ROP Ag electrode. The Ag electrode was applied to fabricate top-gate/bottom-contact poly(3-hexylthiophene) OTFT devices, which showed reproducible OTFT characteristics such as the field-effect mobility, threshold voltage, and an on/off-current ratio of -10(-3) cm2/Vs, 0.36 V, and -10(2), respectively. PMID:22849104

  2. Measurement of local convective heat transfer coefficients from a smooth and roughened NACA-0012 airfoil: Flight test data

    NASA Technical Reports Server (NTRS)

    Newton, James E.; Vanfossen, G. James; Poinsatte, Phillip E.; Dewitt, Kenneth J.

    1988-01-01

    Wind tunnels typically have higher free stream turbulence levels than are found in flight. Turbulence intensity was measured to be 0.5 percent in the NASA Lewis Icing Research Tunnel (IRT) with the cloud making sprays off and around 2 percent with cloud making equipment on. Turbulence intensity for flight conditions was found to be too low to make meaningful measurements for smooth air. This difference between free stream and wing tunnel conditions has raised questions as to the validity of results obtained in the IRT. One objective of these tests was to determine the effect of free stream turbulence on convective heat transfer for the NASA Lewis LEWICE ice growth prediction code. These tests provide in-flight heat transfer data for a NASA-0012 airfoil with a 533 cm chord. Future tests will measure heat transfer data from the same airfoil in the Lewis Icing Research Tunnel. Roughness was obtained by the attachment of small, 2 mm diameter hemispheres of uniform size to the airfoil in three different patterns. Heat transfer measurements were recorded in flight on the NASA Lewis Twin Otter Icing Research Aircraft. Measurements were taken for the smooth and roughened surfaces at various aircraft speeds and angles of attack up to four degrees. Results are presented as Frossling number versus position on the airfoil for various roughnesses and angles of attack.

  3. Measurement of local convective heat transfer coefficients from a smooth and roughened NACA-0012 airfoil - Flight test data

    NASA Technical Reports Server (NTRS)

    Van Fossen, G. James; De Witt, Kenneth J.; Newton, James E.; Poinsatte, Phillip E.

    1988-01-01

    Wind tunnels typically have higher free stream turbulence levels than are found in flight. Turbulence intensity was measured to be 0.5 percent in the NASA Lewis Icing Research Tunnel (IRT) with the cloud making sprays off and around 2 percent with cloud making equipment on. Turbulence intensity for flight conditions was found to be too low to make meaningful measurements for smooth air. This difference between free stream and wind tunnel conditions has raised questions as to the validity of results obtained in the IRT. One objective of these tests was to determine the effect of free stream turbulence on convective heat transfer for the NASA Lewis LEWICE ice growth prediction code. These tests provide in-flight heat transfer data for a NASA-0012 airfoil with a 533 cm chord. Future tests will measure heat transfer data from the same airfoil in the Lewis Icing Research Tunnel. Roughness was obtained by the attachment of small, 2 mm diameter hemispheres of uniform size to the airfoil in three different patterns. Heat transfer measurements were recorded in flight on the NASA Lewis Twin Otter Icing Research Aircraft. Measurements were taken for the smooth and roughened surfaces at various aircraft speeds and angles of attack up to four degrees. Results are presented as Frossling number versus position on the airfoil for various roughnesses and angles of attack.

  4. Persistent monolayer-scale chemical ordering in Si1-xGex heteroepitaxial films during surface roughening and strain relaxation

    NASA Astrophysics Data System (ADS)

    Amatya, J. M.; Floro, J. A.

    2015-12-01

    Chemical ordering in semiconductor alloys could modify thermal and electronic transport, with potential benefits to thermoelectric properties. Here, metastable ordering that occurs during heteroepitaxial growth of Si1-xGex thin film alloys on Si(001) and Ge(001) substrates is investigated. A parametric study was performed to study how strain, surface roughness, and growth parameters affect the order parameter during the alloy growth. The order parameter for the alloy films was carefully quantified using x-ray diffraction, taking into account an often-overlooked issue associated with the presence of multiple spatial variants associated with ordering along equivalent <111> directions. Optimal ordering was observed in the films having the smoothest surfaces. Extended strain relaxation is suggested to reduce the apparent order through creation of anti-phase boundaries. Ordering surprisingly persists even when the film surface extensively roughens to form {105} facets. Growth on deliberately miscut Si(001) surfaces does not affect the volume-averaged order parameter but does impact the relative volume fractions of the equivalent ordered variants in a manner consistent with geometrically necessary changes in step populations. These results provide somewhat self-contradictory implications for the role of step edges in controlling the ordering process, indicating that our understanding is still incomplete.

  5. Effect of input power and gas pressure on the roughening and selective etching of SiO2/Si surfaces in reactive plasmas

    NASA Astrophysics Data System (ADS)

    Zhong, X. X.; Tam, E.; Huang, X. Z.; Colpo, P.; Rossi, F.; Ostrikov, K.

    2010-09-01

    We report on the application low-temperature plasmas for roughening Si surfaces which is becoming increasingly important for a number of applications ranging from Si quantum dots to cell and protein attachment for devices such as "laboratory on a chip" and sensors. It is a requirement that Si surface roughening is scalable and is a single-step process. It is shown that the removal of naturally forming SiO2 can be used to assist in the roughening of the surface using a low-temperature plasma-based etching approach, similar to the commonly used in semiconductor micromanufacturing. It is demonstrated that the selectivity of SiO2/Si etching can be easily controlled by tuning the plasma power, working gas pressure, and other discharge parameters. The achieved selectivity ranges from 0.4 to 25.2 thus providing an effective means for the control of surface roughness of Si during the oxide layer removal, which is required for many advance applications in bio- and nanotechnology.

  6. Effect of input power and gas pressure on the roughening and selective etching of SiO{sub 2}/Si surfaces in reactive plasmas

    SciTech Connect

    Zhong, X. X.; Huang, X. Z.; Tam, E.; Ostrikov, K.; Colpo, P.; Rossi, F.

    2010-09-15

    We report on the application low-temperature plasmas for roughening Si surfaces which is becoming increasingly important for a number of applications ranging from Si quantum dots to cell and protein attachment for devices such as 'laboratory on a chip' and sensors. It is a requirement that Si surface roughening is scalable and is a single-step process. It is shown that the removal of naturally forming SiO{sub 2} can be used to assist in the roughening of the surface using a low-temperature plasma-based etching approach, similar to the commonly used in semiconductor micromanufacturing. It is demonstrated that the selectivity of SiO{sub 2}/Si etching can be easily controlled by tuning the plasma power, working gas pressure, and other discharge parameters. The achieved selectivity ranges from 0.4 to 25.2 thus providing an effective means for the control of surface roughness of Si during the oxide layer removal, which is required for many advance applications in bio- and nanotechnology.

  7. Electrochemical Study and Applications of Selective Electrodeposition of Silver on Quantum Dots.

    PubMed

    Martín-Yerga, Daniel; Rama, Estefanía Costa; Costa-García, Agustín

    2016-04-01

    In this work, selective electrodeposition of silver on quantum dots is described. The particular characteristics of the nanostructured silver thus obtained are studied by electrochemical and microscopic techniques. On one hand, quantum dots were found to catalyze the silver electrodeposition, and on the other hand, a strong adsorption between electrodeposited silver and quantum dots was observed, indicated by two silver stripping processes. Nucleation of silver nanoparticles followed different mechanisms depending on the surface (carbon or quantum dots). Voltammetric and confocal microscopy studies showed the great influence of electrodeposition time on surface coating, and high-resolution transmission electron microscopy (HRTEM) imaging confirmed the initial formation of Janus-like Ag@QD nanoparticles in this process. By use of moderate electrodeposition conditions such as 50 μM silver, -0.1 V, and 60 s, the silver was deposited only on quantum dots, allowing the generation of localized nanostructured electrode surfaces. This methodology can also be employed for sensing applications, showing a promising ultrasensitive electrochemical method for quantum dot detection. PMID:26910270

  8. Bioanalysis with Potentiometric Membrane Electrodes.

    ERIC Educational Resources Information Center

    Rechnitz, G. A.

    1982-01-01

    Discusses major themes and interrelationships common to bioselective potentiometric membrane electrodes including the nature of bioselective electrodes, applications, and future prospects. Includes tables on traditional ion-selective membrane electrodes, nontraditional electrodes, and typical biocatalytic potentiometric electrodes. (Author/JN)

  9. Ion-Selective Electrodes.

    ERIC Educational Resources Information Center

    Arnold, Mark A.; Meyerhoff, Mark E.

    1984-01-01

    Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

  10. Fundamental electrode kinetics

    NASA Technical Reports Server (NTRS)

    Elder, J. P.

    1968-01-01

    Report presents the fundamentals of electrode kinetics and the methods used in evaluating the characteristic parameters of rapid-charge transfer processes at electrode-electrolyte interfaces. The concept of electrode kinetics is outlined, followed by the principles underlying the experimental techniques for the investigation of electrode kinetics.

  11. Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

    NASA Astrophysics Data System (ADS)

    Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

    2009-04-01

    In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies

  12. Design of dual working electrodes for concentration process in metalloimmunoassay.

    PubMed

    Hori, Nobuyasu; Chikae, Miyuki; Kirimura, Hiroya; Takamura, Yuzuru

    2016-10-01

    Electrochemical immunosensing, particularly through a metalloimmunoassay, is a promising approach for development of point-of-care (POC) diagnostics devices. This study investigated the structure of dual working electrodes (W1 and W2), used in a silver nanoparticles-labeled sandwich-type immunoassay and silver concentration process, paying special attention to the position of W1 relative to W2. The new structures of the dual working electrodes were fabricated for efficient silver concentration and evaluated experimentally, which showed that the duration of prereduction before current measurement decreased from 480 s to 300 s by transforming the position of W1 from 1 line to 2 lines or 6 parts. The experimental results were also compared with numerical simulations based on three-dimensional diffusion, and the prereduction step almost followed the three-dimensional diffusion equation. Using numerical simulations, the ideal structures of dual working electrodes were designed based on relationships between the structures and duration of prereduction or the LOD. In the case of 36 lines at an area ratio of W1 to W1 + W2 of 1 to 10, the prereduction duration decreased to 96 s. The dual working electrodes designed in this study promise to shorten the total analysis time and lower the LOD for POC diagnostics. PMID:27572238

  13. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are about "strange…

  14. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  15. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

    Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  16. Electrode Evaporation Effects on Air Arc Behavior

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Chen, Degui; Li, Rui; Wu, Yi; Niu, Chunping

    2008-06-01

    A numerical study of the effects of copper and silver vapours on the air arc behavior is performed. The commercial software FLUENT is adapted and modified to develop a two-dimensional magneto-hydrodynamic (MHD) models of arc with the thermodynamic properties and transport coefficients, net emission coefficient for the radiation model of 99% ai-1% Cu, 99% air-1% Ag, and pure air, respectively. The simulation result demonstrates that vaporization of the electrode material may cool the arc center region and reduce the arc velocity. The effects of Ag vapour are stronger compared to those of Cu vapour.

  17. Variability of electrode positions using electrode caps.

    PubMed

    Atcherson, Samuel R; Gould, Herbert Jay; Pousson, Monique A; Prout, Tina M

    2007-01-01

    We investigated the variability of electrode positions for a multi-channel, custom electrode cap placed onto participants' heads without taking scalp measurements. The electrode positions were digitized in a three-dimensional space for 10 young adult participants on three separate occasions. Positional variability was determined for 15 selected electrodes within the three-dimensional preauricular-nasion (PAN) coordinate system and from this system, angular coordinate variability was also determined. The standard deviations of the 15 selected electrodes ranged from 3.0 to 12.7 mm in the PAN system. These data resulted in a variability of 2.0 degrees to 10.4 degrees among the angular coordinates. The measurements indicated slightly greater variability of electrode positions compared to studies when electrodes were placed using scalp measurements. The implication of this study is that the use of electrode caps may not be appropriate when electroencephalographic (EEG) or evoked potential (EP) techniques depend on accurate electrode placement. Additionally, if a longitudinal study is performed, electrode locations should be checked to ensure that they conform with previous sessions. PMID:17929157

  18. HSPES membrane electrode assembly

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

    2000-01-01

    An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

  19. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  20. Surface-enhanced Raman scattering and atomic force microscopy of brass electrodes in sulfuric acid solution containing benzotriazole and chloride ion

    SciTech Connect

    Rubim, J.C.; Kim, J.; Henderson, E.; Cotton, T.M. Ames Lab., IA Iowa State Univ., Ames )

    1993-01-01

    Three different methods were used to roughen brass (Cu/Zn = 67/33) electrodes in 0.5 M H[sub 2]SO[sub 4] containing 1.0 mM benzotriazole (BTAH): (1) polarization at +0.05 V vs. saturated calomel for 5 min; (2) immersion in the above solution for six hours; and (3) oxidation-reduction cycling in the presence of chloride ion. The surfaces prepared by the first two methods exhibited surface-enhanced Raman scattering (SERS) spectra of the polymeric complex [Cu(I)BTA][sub s]. The SERS spectrum obtained from electrodes prepared by the third method is very similar to that of [Cu(I)CIBTAH][sub 4]. Examination of the electrodes by atomic force microscopy (AFM) showed that a large number of grain boundary sites are formed by the roughening processes. This effect is attributed to the loss of zinc, which occurs during corrosion of the mirror-like, polished brass electrode surface in the sulfuric acid solution. 11 refs., 5 figs.

  1. Oxygen reduction on Ni, Ag, and Cu meniscus electrodes in molten carbonate

    SciTech Connect

    Ogura, Hiroyuki; Shirogami, Tamotsu

    1994-12-31

    The oxygen reduction pathways in molten carbonates have been investigated by analyzing the charge transfer resistances of the i-V curves on the meniscus electrodes of Ni, Cu, and Ag screens at 550 C. The electrochemical reduction pathways of oxygen at the meniscus electrode were found to be different depending on the electrode materials. For the Ni meniscus electrode system, the reactive material of charge transfer is the lithium doped nickel oxide, for the Ag system that is the silver oxide ion, and for the Cu system that is peroxide ion, respectively.

  2. Advanced silver zinc battery development for the SRB and ET range safety subsystems

    NASA Technical Reports Server (NTRS)

    Adamedes, Zoe

    1994-01-01

    This document presents in viewgraph format the design and development of silver zinc (AgZn) batteries for the solid rocket booster (SRB) and external tank (ET) range safety subsystems. Various engineering techniques, including composite separator systems, new electrode processing techniques, and new restraint techniques, were used to meet difficult requirements.

  3. Advanced silver zinc battery development for the SRB and ET range safety subsystems

    NASA Astrophysics Data System (ADS)

    Adamedes, Zoe

    1994-02-01

    This document presents in viewgraph format the design and development of silver zinc (AgZn) batteries for the solid rocket booster (SRB) and external tank (ET) range safety subsystems. Various engineering techniques, including composite separator systems, new electrode processing techniques, and new restraint techniques, were used to meet difficult requirements.

  4. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates.

    PubMed

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-01-01

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the "melt-back" effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude. PMID:26487465

  5. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates

    PubMed Central

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-01-01

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the “melt-back” effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude. PMID:26487465

  6. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  7. Micromachined electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  8. Controlled porosity in electrodes

    SciTech Connect

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  9. Nanoimprint-assisted fabrication of high haze metal mesh electrode for solar cells

    NASA Astrophysics Data System (ADS)

    Iwahashi, Takashi; Yang, Rong; Okabe, Noriaki; Sakurai, Junpei; Lin, Jun; Matsunaga, Daisuke

    2014-12-01

    We propose a concept of transparent electrode for solar cells surpassing conventional transparent conductive oxide. Transparent electrode requires low electrical resistivity, high optical transparency, and high optical haze. Although transparent conductive oxide by chemical vapor deposition is widely used as a transparent electrode for solar cells, a breakthrough of the trade-off between electrical and optical properties is required for further improvement of solar cell efficiency. We demonstrate solution-processed electrode fabrication by using nanoimprint technology and metal nanoparticle ink. Silver mesh electrode is self-aligned on nanoimprinted texture with concave pattern as a template for mesh grid. Our electrode concept can realize desired high optical haze by nanoimprinted texture, as well as low electrical resistivity and high optical transparency by metal mesh electrode simultaneously, which boosts solar cell efficiency.

  10. Hydrometallurgical recovery of silver from waste silver oxide button cells

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000 °C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600 V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated.

  11. Superwettability-Induced Confined Reaction toward High-Performance Flexible Electrodes.

    PubMed

    Xiong, Weiwei; Liu, Hongliang; Zhou, Yahong; Ding, Yi; Zhang, Xiqi; Jiang, Lei

    2016-05-18

    To find a general strategy to realize confinement of the conductive layer for high-performance flexible electrodes, with improved interfacial adhesion and high conductivity, is of important scientific significance. In this work, superwettability-induced confined reaction is used to fabricate high-performance flexible Ag/polymer electrodes, showing significantly improved silver conversion efficiency and interfacial adhesion. The as-prepared flexible electrodes by superhydrophilic polymeric surface under oil are highly conductive with an order of magnitude higher than the Ag/polymer electrodes obtained from original polymeric surface. The high conductivity achieved via superhydrophilic confinement is ascribed to the fact that the superhydrophilic polymeric surface can enhance the reaction rate of silver deposition and reduce the size of silver nanoparticles to achieve the densest packing. This new approach will provide a simple method to fabricate flexible and highly conductive Ag/polymer electrodes with excellent adhesion between the conductive layer and the substrate, and can be extended to other metal/polymeric electrodes or alloy/polymeric electrodes. PMID:27115913

  12. Positive electrode current collector for liquid metal cells

    DOEpatents

    Shimotake, Hiroshi; Bartholme, Louis G.

    1984-01-01

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  13. Positive-electrode current collector for liquid-metal cells

    DOEpatents

    Shimotake, H.; Bartholme, L.G.

    1982-09-27

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  14. Surface-enhanced Raman microspectroscopy at electrode surfaces

    SciTech Connect

    Hembree D.M. Jr.; Oswald, J.C.; Smyrl, N.R.

    1987-02-01

    Surface-enhanced Raman microspectroscopy has been developed as a technique for characterizing processes occurring at the electrode/electrolyte interface. A spectroelectrochemical cell was designed to obtain Raman spectra of electrochemical species with the use of microscope optics, which allowed unambiguous placement of laser focus at the electrode surface with spatial resolution on the order of 1 ..mu..m. It was also possible to visually inspect the surface morphology of the electrode with the use of the Raman microscope in the reflected-light mode. The capabilities of the spectroelectrochemical cell were demonstrated by observation of surface-enhanced Raman scattering (SERS) for a variety of model systems (pyridine, pyridinium ion, potassium cyanide) with the use of silver, copper, and nickel electrodes. The electrochemical behavior of a commercially important gold electroplating process is also reported.

  15. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  16. Genetics Home Reference: Russell-Silver syndrome

    MedlinePlus

    ... Genetics Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Russell-Silver syndrome is a growth disorder characterized by slow ...

  17. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  18. Electroencephalogram measurement using polymer-based dry microneedle electrode

    NASA Astrophysics Data System (ADS)

    Arai, Miyako; Nishinaka, Yuya; Miki, Norihisa

    2015-06-01

    In this paper, we report a successful electroencephalogram (EEG) measurement using polymer-based dry microneedle electrodes. The electrodes consist of needle-shaped substrates of SU-8, a silver film, and a nanoporous parylene protective film. Differently from conventional wet electrodes, microneedle electrodes do not require skin preparation and a conductive gel. SU-8 is superior as a structural material to poly(dimethylsiloxane) (PDMS; Dow Corning Toray Sylgard 184) in terms of hardness, which was used in our previous work, and facilitates the penetration of needles through the stratum corneum. SU-8 microneedles can be successfully inserted into the skin without breaking and could maintain a sufficiently low skin-electrode contact impedance for EEG measurement. The electrodes successfully measured EEG from the frontal pole, and the quality of acquired signals was verified to be as high as those obtained using commercially available wet electrodes without any skin preparation or a conductive gel. The electrodes are readily applicable to record brain activities for a long period with little stress involved in skin preparation to the users.

  19. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  20. Organic devices based on nickel nanowires transparent electrode

    PubMed Central

    Kim, Jeongmo; da Silva, Wilson Jose; bin Mohd Yusoff, Abd. Rashid; Jang, Jin

    2016-01-01

    Herein, we demonstrate a facile approach to synthesize long nickel nanowires and discuss its suitability to replace our commonly used transparent electrode, indium-tin-oxide (ITO), by a hydrazine hydrate reduction method where nickel ions are reduced to nickel atoms in an alkaline solution. The highly purified nickel nanowires show high transparency within the visible region, although the sheet resistance is slightly larger compared to that of our frequently used transparent electrode, ITO. A comparison study on organic light emitting diodes and organic solar cells, using commercially available ITO, silver nanowires, and nickel nanowires, are also discussed. PMID:26804335

  1. Organic devices based on nickel nanowires transparent electrode

    NASA Astrophysics Data System (ADS)

    Kim, Jeongmo; da Silva, Wilson Jose; Bin Mohd Yusoff, Abd. Rashid; Jang, Jin

    2016-01-01

    Herein, we demonstrate a facile approach to synthesize long nickel nanowires and discuss its suitability to replace our commonly used transparent electrode, indium-tin-oxide (ITO), by a hydrazine hydrate reduction method where nickel ions are reduced to nickel atoms in an alkaline solution. The highly purified nickel nanowires show high transparency within the visible region, although the sheet resistance is slightly larger compared to that of our frequently used transparent electrode, ITO. A comparison study on organic light emitting diodes and organic solar cells, using commercially available ITO, silver nanowires, and nickel nanowires, are also discussed.

  2. Hexacyanoferrate-based composite ion-sensitive electrodes for voltammetry.

    PubMed

    Düssel, H; Dostal, A; Scholz, F

    1996-04-01

    Composite electrodes made of graphite, paraffin and metal hexacyanoferrates exhibit a voltammetric response of the hexacyanoferrate ions, the potential of which depends linearly on the logarithm of concentration of alkali and alkaline-earth metal ions. This behaviour has been observed on account of the fact that the electrochemical reaction is accompanied by an exchange of these ions between the solution and the zeolitic lattice of the hexacyanoferrates for charge compensation. The voltammetric determination of the formal potential of these electrodes in a solution allows the quantitative analysis of the ions which are exchanged between the metal hexacyanoferrates and the aqueous solutions. Iron(III), copper(II), silver(I), nickel(II) and cadmium(II) hexacyanoferrates have been studied for the determination of H(+), Li(+), Na(+), K(+), Rb(+), Cs(+), NH(+)(4), Mg(2+), Ca(2+) and Ba(2+). In some cases, the selectivity constants are as low as 3.10(-4), or even so small that their exact value is inaccessible. Electrodes made of iron (III), copper (II), silver (I), nickel (II) and cadmium (II) hexacyanoferrates are most suitable for the determination of potassium ions. Electrodes with nickel (II) and cadmium (II) hexacyanoferrates are also suitable for the determination of caesium ions. The working range of the electrodes also depends on the conductivity of the solutions and can range from 10(-5) to 1 mol l(-1). Typical standard deviations of the potential measurements are 3 mV. PMID:15045452

  3. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  4. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  5. Nanostructured silver-gold bimetallic SERS substrates for selective identification of bacteria in human blood.

    PubMed

    Sivanesan, Arumugam; Witkowska, Evelin; Adamkiewicz, Witold; Dziewit, Łukasz; Kamińska, Agnieszka; Waluk, Jacek

    2014-03-01

    Surface-enhanced Raman spectroscopy (SERS) is a potentially important tool in the rapid and accurate detection of pathogenic bacteria in biological fluids. However, for diagnostic application of this technique, it is necessary to develop a highly sensitive, stable, biocompatible and reproducible SERS-active substrate. In this work, we have developed a silver-gold bimetallic SERS surface by a simple potentiostatic electrodeposition of a thin gold layer on an electrochemically roughened nanoscopic silver substrate. The resultant substrate was very stable under atmospheric conditions and exhibited the strong Raman enhancement with the high reproducibility of the recorded SERS spectra of bacteria (E. coli, S. enterica, S. epidermidis, and B. megaterium). The coating of the antibiotic over the SERS substrate selectively captured bacteria from blood samples and also increased the Raman signal in contrast to the bare surface. Finally, we have utilized the antibiotic-coated hybrid surface to selectively identify different pathogenic bacteria, namely E. coli, S. enterica and S. epidermidis from blood samples. PMID:24419003

  6. A novel non-enzyme hydrogen peroxide sensor based on catalytic reduction property of silver nanowires.

    PubMed

    Qin, Xia; Wang, Huicai; Miao, Zhiying; Li, Junli; Chen, Qiang

    2015-07-01

    A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed based on silver nanowires modified Pt electrode. The sensor was fabricated by simple casting of silver nanowires (Ag NWs) aqueous solution on a Pt electrode. Silver nanowires were synthesized by an l-cysteine-assisted poly (vinyl pyrrolidone) (PVP)-mediated polyol route. UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to investigate the prepared nanowires. The electrochemical properties of H2O2 sensor were evaluated by cyclic voltammetry (CV) and chronoamperometry. The as-obtained silver nanowires exhibited favorable electroreduction activity toward H2O2, and results indicated that the Ag NWs modified Pt (Ag NWs/Pt) electrode might be gifted from CV scanning with higher surface area and more active sites that afford more effective surface exposure in the electrode-electrolyte interface and consequently improved electrochemical properties. At the applied potential of -0.2V vs. Ag/AgCl, the Ag NWs/Pt electrode as an enzyme-free sensor exhibited a wide linear range of 0.5μM-30mM to H2O2, with a remarkable sensitivity of 9.45μA/mM, a detection limit of 0.2μM estimated at a signal-to-noise ratio of 3 and fast response time (within 5s). Moreover, it showed good reproducibility, anti-interferant ability and long-term stability. The excellent performance of the sensor might be attributed to the well-defined silver nanowires with special catalytic activity. PMID:25882408

  7. Angle-specific transparent conducting electrodes with metallic gratings

    SciTech Connect

    Rivolta, N. X. A. Maes, B.

    2014-08-07

    Transparent conducting electrodes, which are not made from indium tin oxide, and which display a strong angular dependence are useful for various technologies. Here, we introduce a tilted silver grating that combines a large conductance with a strong and angle-specific transmittance. When the light incidence angle matches the tilt angle of the grating, transmittance is close to the maximum along a very broadband range. We explain the behavior through simulations that show in detail the plasmonic and interference effects at play.

  8. Corneal-shaping electrode

    DOEpatents

    Doss, James D.; Hutson, Richard L.

    1982-01-01

    The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

  9. Improved biomedical electrode

    NASA Technical Reports Server (NTRS)

    Frost, J. D., Jr.

    1972-01-01

    Newly designed electrode is prefilled, disposable, electrolyte-saturated spong. New design permits longe periods of storage without deterioration, and readiness in matter of seconds. Electrodes supply signals for electroencephalogram, electro-oculogram, and electrocardiogram.

  10. Printed silver nanowire antennas with low signal loss at high-frequency radio.

    PubMed

    Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

    2012-05-21

    Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film. PMID:22522460

  11. Compartmented electrode structure

    DOEpatents

    Vissers, Donald R.; Shimotake, Hiroshi; Gay, Eddie C.; Martino, Fredric J.

    1977-06-14

    Electrodes for secondary electrochemical cells are provided with compartments for containing particles of the electrode reactant. The compartments are defined by partitions that are generally impenetrable to the particles of reactant and, in some instances, to the liquid electrolyte used in the cell. During cycling of the cell, reactant material initially loaded into a particular compartment is prevented from migrating and concentrating within the lower portion of the electrode or those portions of the electrode that exhibit reduced electrical resistance.

  12. Insulated ECG electrodes

    NASA Technical Reports Server (NTRS)

    Portnoy, W. M.; David, R. M.

    1973-01-01

    Insulated, capacitively coupled electrode does not require electrolyte paste for attachment. Other features of electrode include wide range of nontoxic material that may be employed for dielectric because of sputtering technique used. Also, electrode size is reduced because there is no need for external compensating networks with FET operational amplifier.

  13. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  14. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  15. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  16. Near-electrode imager

    DOEpatents

    Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, II, Rex E.

    2000-01-01

    An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager uses the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

  17. Fuel cell electrodes

    DOEpatents

    Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

    2015-06-23

    A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

  18. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  19. Microresonator electrode design

    DOEpatents

    Olsson, III, Roy H.; Wojciechowski, Kenneth; Branch, Darren W.

    2016-05-10

    A microresonator with an input electrode and an output electrode patterned thereon is described. The input electrode includes a series of stubs that are configured to isolate acoustic waves, such that the waves are not reflected into the microresonator. Such design results in reduction of spurious modes corresponding to the microresonator.

  20. Near-Electrode Imager

    SciTech Connect

    Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, Rex E.,II

    1999-05-01

    An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager use the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

  1. Aerospace electrode line

    NASA Technical Reports Server (NTRS)

    Miller, L.

    1980-01-01

    A facility which produces electrodes for spacecraft power supplies is described. The electrode assembly procedures are discussed. A number of design features in the production process are reported including a batch operation mode and an independent equipment module design approach for transfering the electrode materials from process tank to process tank.

  2. Silver-zinc: status of technology and applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Makovetski, B.; Russell, S. J.; Serenyi, J. R.; Williams, D. C.

    Michel Yardney and Professor Henri André developed the first practical silver-zinc battery more than 55 years ago. Since then, primary and rechargeable silver-zinc batteries have attracted a variety of applications due to their high specific energy/energy density, proven reliability and safety, and the highest power output per unit weight and volume of all commercially available batteries. Although significant improvements have been achieved on traditional systems such as lead-acid and nickel/cadmium, and in spite of the advent of new electrochemistries such as lithium-ion and nickel/metal hydride, many users still rely on silver-zinc to satisfy their most demanding and critical requirements. Over the past few years, several of the internal components have been subject to many studies which resulted in significant improvements in the battery wet life and cycle life. Specifically, these include new separator materials which offer an alternative to the cellulosic membranes, improvements to the zinc electrode that include additives that help reduce shape-change and dendritic growth, and to a lesser extent, process changes to the silver electrode and additives to the electrolyte. In comparison, the commonly used secondary systems are lead-acid, nickel/cadmium, nickel/metal hydride, and lithium-ion. Each has attributes which make them desirable for certain applications. Where low cost, high voltage, and high rate capability is required, the lead-acid battery is an obvious choice whenever size and weight are not critical. For applications requiring longer wet life, moderate rate capability, and high cycle life, nickel/cadmium or nickel/metal hydride can be used in spite of their poor charge retention and higher costs. Relatively newer systems are also available such as lithium-ion or lithium polymer technology which are preferred for their high voltage and excellent cycle life. Among the disadvantages of these systems are higher costs, limited configurations (usually

  3. Comparison of nanostructured silver-modified silver and carbon ultramicroelectrodes for electrochemical detection of nitrate.

    PubMed

    Lotfi Zadeh Zhad, Hamid R; Lai, Rebecca Y

    2015-09-10

    We report the use of silver (Ag)-modified carbon and Ag ultramicroelectrodes (UMEs) for electrochemical detection of nitrate. We investigated several methods for electrodeposition of Ag; our results show that the addition of a complexation agent (ammonium sulfate) in the Ag deposition solution is necessary for electrodeposition of nanostructured Ag that adheres well to the electrode. The electrodeposited Ag on both types of electrodes has branch-like structures that are well-suited for electrocatalytic reduction of nitrate. The use of UMEs is advantageous; the sigmoidal-shaped cyclic voltammogram allows for sensitive detection of nitrate by reducing the capacitive current, as well as enabling easy quantification of the nitrate reduction current. Both cyclic voltammetry and chronoamperometry were used to characterize the electrodes; and independent of the electrochemical interrogation technique, both UMEs were found to have a wide linear dynamic range (4-1000 μM) and a low limit of detection (3.2-5.1 μM). More importantly, they are reusable up to ∼100 interrogation cycles and are selective enough to be used for direct detection of nitrate in a synthetic aquifer sample without any sample pretreatment and/or pH adjustment. PMID:26388486

  4. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  5. Nanoindentation studies on silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Saha, Dhriti Ranjan; Mandal, Amrita; Mitra, Sreemanta; Mada, Mykanth Reddy; Boughton, Philip; Bandyopadhyay, Sri; Chakravorty, Dipankar

    2013-06-01

    Nanodimensional metallic silver was grown by electrodeposion technique in a semi solid polymer matrix of polyacrylamide. The whole structure looks like dendronic. The average particle diameter of the as grown metallic silver is 13 nm. Nanoindentation study of these nanoparticles shows modulus and hardness value as 103.93 GPa and 3.12 GPa respectively.

  6. Spark gap electrode erosion

    NASA Astrophysics Data System (ADS)

    Krompholz, H.; Kristiansen, M.

    1984-12-01

    The results of a one-year contract on electrode erosion phenomena are summarized. The arc voltage drop in a spark gap was measured for various electrode, gas, and pressure combinations. A previously developed model of self breakdown voltage distribution was extended. A jet model for electrode erosion was proposed and an experimental arrangement for testing the model was constructed. The effects of inhomogeneities and impurities in the electrodes were investigated. Some of the work described here is scheduled for completion in 1985 under a current grant (AFOSR 84-0032). The areas of investigation described here include: (1) Self breakdown voltage distributions; (2) Electrode erosion; (3) Spark gap voltage recovery.

  7. Indium-free organic thin-film solar cells using a plasmonic electrode

    NASA Astrophysics Data System (ADS)

    Takatori, Kentaro; Nishino, Takayuki; Okamoto, Takayuki; Takei, Hiroyuki; Ishibashi, Koji; Micheletto, Ruggero

    2016-05-01

    We propose a new kind of organic solar cell (OSC) that substitutes the standard indium tin oxide (ITO) electrode with a silver layer with randomly arranged circular nanoholes (plasmonic electrode). The quasi-random structure in the silver layer efficiently converts wideband incident light into surface plasmon polaritons propagating along the surface of the silver film. In this way, the converted surface plasmon polaritons enhance light absorption in the active layer. We describe in detail the fabrication process we used and we give a thorough report of the resulting optical characteristics and performances. Although the transmittance of the plasmonic electrode is approximately one-third of that of the ITO electrodes, the power conversion efficiency of the OSCs with our plasmonic electrode is comparable to that of conventional inverted solar cells using ITO electrodes. Moreover, the obtained incident photon to current efficiency was better than that of the inverted solar cells in the wavelength regions around 400 nm and over 620 nm.

  8. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  9. Foldable Transparent Substrates with Embedded Electrodes for Flexible Electronics.

    PubMed

    Kim, Jin-Hoon; Park, Jin-Woo

    2015-08-26

    We present highly flexible transparent electrodes composed of silver nanowire (AgNW) networks and silica aerogels embedded into UV-curable adhesive photopolymers (APPs). Because the aerogels have an extremely high surface-to-volume ratio, the enhanced van der Waals forces of the aerogel surfaces result in more AgNWs being uniformly coated onto a release substrate and embedded into the APP when mixed with an AgNW solution at a fixed concentration. The uniform distribution of the embedded composite electrodes of AgNWs and aerogels was verified by the Joule heating test. The APP with the composite electrodes has a lower sheet resistance (Rs) and a better mechanical stability compared with APP without aerogels. The APP with the embedded electrodes is a freestanding flexible substrate and can be used as an electrode coating on a polymer substrate, such as polydimethylsiloxane and polyethylene terephthalate. On the basis of the bending test results, the APPs with composite electrodes were sufficiently flexible to withstand a 1 mm bending radius (rb) and could be foldable with a slight change in Rs. Organic light emitting diodes were successfully fabricated on the APP with the composite electrodes, indicating the strong potential of the proposed flexible TEs for application as highly flexible transparent conductive substrates. PMID:26258906

  10. Hybrid surface roughening modes during low-temperature heteroepitaxy: Growth of fully-strained metastable Ge{sub 1-x}Sn{sub x} alloys on Ge(001)2x1

    SciTech Connect

    Desjardins, P.; Spila, T.; Guerdal, O.; Taylor, N.; Greene, J. E.

    1999-12-15

    Fully-strained single-crystal metastable Ge{sub 1-x}Sn{sub x} alloys were grown on Ge(001) up to their critical epitaxial thickness values t{sub epi}(x) in order to probe surface roughening pathways leading to heteroepitaxial breakdown during low-temperature molecular-beam epitaxy under large compressive strain. All films with x>0.09 have comparable roughnesses while films with x<0.09 are considerably rougher with larger lateral feature sizes. Roughening rates increase with increasing x for films with x>0.09 due to a new hybrid relaxation path which only becomes accessible under high strain as kinetic roughening provides surface oscillations on lateral length scales that allow bulk relaxation through strain-induced islanding at growth temperatures where it could not otherwise proceed. (c) 1999 The American Physical Society.

  11. Silver clusters and chemistry in zeolites

    SciTech Connect

    Sun, T.; Seff, K. . Dept. of Chemistry)

    1994-06-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  12. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  13. Novel Conductive Carbon Black and Polydimethlysiloxane ECG Electrode: A Comparison with Commercial Electrodes in Fresh, Chlorinated, and Salt Water.

    PubMed

    Noh, Yeonsik; Bales, Justin R; Reyes, Bersain A; Molignano, Jennifer; Clement, Amanda L; Pins, George D; Florian, John P; Chon, Ki H

    2016-08-01

    In this study, we evaluated the performance of two novel conductive carbon black (CB) and polydimethlysiloxane (PDMS) bio-potential electrodes, with and without an integrated flexible copper mesh, against commercially available electrodes (Polar(®) textile, Silver-coated textile, and carbon rubber). The electrodes were tested in three types of water (fresh/unfiltered, chlorinated, and salt water). Our testing revealed that our CB/PDMS electrode with integrated copper mesh provided a high-fidelity ECG signal morphologies without any amplitude degradation in all of the types of water tested (N = 10). The non-meshed CB/PDMS electrodes were also subjected to a long-term durability test by the US Navy SCUBA divers during which the electrodes maintained ECG signal quality for a 6 h period of continuous use. The results of a material degradation analysis revealed the CB/PDMS composite material does not exhibit significant changes in physical integrity after prolonged exposure to the test conditions. The newly developed meshed CB/PDMS electrodes have the potential to be used in a wide variety of both dry and wet environments including the challenge of obtaining ECG signals in salt water environments. PMID:26769718

  14. Thermal stability of PLD grown silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  15. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

    Over the past few decades, advances in biology and electronics have resulted in an enormous increase in the screening rate of new compounds and in the capacity to synthesize vast numbers of new compounds. The understanding of disease has greatly improved. At the same time, the number of targets (or diseases) for the silver bullets has also increased. Yet, the belief that we have to screen enormous numbers of compounds to find the next new drug continues. Today, disease is understood to be a complex interaction of many systems. This ought to cause us to change our paradigm, but it has not. The fundamental reason for the apparent failure of our drug discovery and development research is that we are operating under the constraints of an out-of-date paradigm. The silver-bullet paradigm has always been a myth. Now is the time to debunk the myth and change the paradigm. Our other option is to continue on as we are and accept that the United States will become obsolete on the playing field of drug discovery.

  16. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  17. Electroretinographic wet electrode.

    PubMed

    Carpi, Federico; Benini, Gabriella; Tomei, Franca; Figliuzzi, Rosa Maria; De Napoli, Alberto

    2009-10-01

    This paper presents the first systematic characterisation of a new electroretinographic (ERG) electrode, recently described. The new 'wet' electrode uses a conducting liquid as a distributed electrical interface between the eye and a solid electronic conductor; the latter detects the ERG potential without any direct contact with the ocular surface. This technique avoids the contact-induced discomfort of both corneal and conjunctival standard electrodes. The wet electrode was tested on 10 volunteers, in comparison with a conjunctival electrode (HK loop), as the most comfortable standard. It was also compared with a cutaneous (cup) electrode, which is even more comfortable, although not standard. Results showed the efficacy of the wet electrode for detecting morphologically accurate ERG responses, with amplitudes respectively analogous and higher of those measured by the conjunctival and cutaneous electrodes. Properties of wet electrodes include: no solid interface with the eye, no need for anaesthesia, intrinsic safety, mechanical and electrical stability against ocular movements, tolerance to misplacements and immunity to lacrimation. As a drawback, the liquid can still be a source of discomfort for some patients and it requires care against possible leakage. All these features suggest a possible use of wet electrodes as an additional tool for ERG procedures, although limited to tests of short duration. PMID:19501539

  18. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  19. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  20. Nucleation, growth, and dissolution of silver nanostructures formed in nanotubular J-aggregates of amphiphilic cyanine dyes.

    PubMed

    Steeg, Egon; Polzer, Frank; Kirmse, Holm; Qiao, Yan; Rabe, Jürgen P; Kirstein, Stefan

    2016-06-15

    Solution fabricated high aspect ratio silver nanowires are of interest because of their usability in plasmonic devices or transparent electrodes. Recently, silver nanowires with diameters of 6.5nm and lengths exceeding tens or hundreds of microns were grown by reduction of silver ions within the inner volume of nanotubular J-aggregates of an amphiphilic cyanine dye. Unlike in other soft template systems, the anisotropic growth of the silver wires is not caused by different screening of the diverse facets of silver crystals. Instead, the shape of the wires replicates the inner space of the tubes without destroying the template. This effect is demonstrated by ex-situ observation of the growth of the silver wires via transmission electron microscopy. The wire growth is initiated by exposure to blue light and starts with small, isolated crystallites within the tubular aggregates. The crystallites grow into pieces of wires that finally coalesce into continuous wires. The growth is mediated by material transport through the membrane-like wall of the dye aggregates. This wall permeability is further demonstrated by dissolution of the silver wires via oxidative etching by addition of sodium chloride. It is concluded that the cyanine double layer wall is permeable for ions such as silver, sodium, chlorine, and water molecules. This permeability permits control of the wire length through the concentration of chlorine when oxygen is removed from the solvent. PMID:27038282

  1. "Bottom-up" transparent electrodes.

    PubMed

    Morag, Ahiud; Jelinek, Raz

    2016-11-15

    Transparent electrodes (TEs) have attracted significant scientific, technological, and commercial interest in recent years due to the broad and growing use of such devices in electro-optics, consumer products (touch-screens for example), solar cells, and others. Currently, almost all commercial TEs are fabricated through "top-down" approaches (primarily lithography-based techniques), with indium tin oxide (ITO) as the most common material employed. Several problems are encountered, however, in this field, including the cost and complexity of TE production using top-down technologies, the limited structural flexibility, high-cost of indium, and brittle nature and low transparency in the far-IR spectral region of ITO. Alternative routes based upon bottom-up processes, have recently emerged as viable alternatives for production of TEs. Bottom up technologies are based upon self-assembly of building blocks - atoms, molecules, or nanoparticles - generating thin patterned films that exhibit both electrical conductivity and optical transparency. In this Feature Article we discuss the recent progress in this active and exciting field, including bottom-up TE systems produced from carbon materials (carbon nanotubes, graphene, graphene-oxide), silver, gold, and other metals. The current hurdles encountered for broader use of bottom-up strategies along with their significant potential are analyzed. PMID:27545510

  2. Electrochemical characterization of binderless, recompressed exfoliated graphite electrodes: electron-transfer kinetics and diffusion characteristics.

    PubMed

    Ramesh, P; Sampath, S

    2003-12-15

    Exfoliated graphite (EG) is prepared by the thermal exfoliation of graphite intercalation compounds at different temperatures. Surface and bulk physicochemical properties of EG are followed by spectroscopic and analytical methods and are observed to be a function of exfoliation temperature. EG particles can be recompressed without any binder and used as surface-renewable electrodes. Surface preparation is accomplished by either polishing or roughening the electrode surface using emery sheets. Effects of exfoliation temperature and the surface preparation on the electron-transfer kinetics and on the diffusion characteristics have been followed by electrochemical methods using several benchmark redox systems. It is found that the electron-transfer kinetics and the diffusion of K(4)[Fe(CN)(6)] are affected by the nature of the EG surface while that of iron(II)(1,10-phenanthroline)(3) and cobalt(II)(1,10-phenanthroline)(3) are not affected by the surface preparation. The redox systems are classified into different groups according to their kinetic sensitivity. Diffusion of electroactive species toward the EG electrodes is found to nonlinear. Current-time plots suggest that the recompressed EG electrodes can be modeled as fractals. PMID:14670057

  3. Polymer glazing for silver mirrors

    SciTech Connect

    Neidlinger, H H; Schissel, P

    1985-07-01

    This paper reports on an evaluation and modification of polymeric glazings to protect silver mirrors. The mirrors were made using Corning 7809 glass as a substrate onto which a thin silver film is deposited. The modified polymeric films are then cast from solution onto the silver. The mirrors were characterized by measuring the hemispherical reflectance and the specular reflectance at 660 nm and selected acceptance angles (7.5 mrad or 3.5 mrad). The mirrors were exposed to environmental degradation using accelerated weathering devices and outdoor exposure. Empirical evidence has demonstrated that polymethylmethacrylate is a stable polymer in a terrestrial environment, but the polymer does not provide adequate protection for the silver reflector. The crucial role in degradation played by ultraviolet (uv) light is shown by several experimental results. It has been demonstrated that uv stabilizers added to the polymer improve the weatherability of mirrors. The relative effectiveness of different stabilizers will be discussed in terms of the weathering modes, retention of optical properties, and effectiveness of the additives. The process for silver deposition influences the reflectance of silver mirrors, and the optical properties depend on subtle relationships between the metallization and the dielectric (polymeric) films that are in contact with the silver.

  4. Silver(I) Ions Ultrasensitive Detection at Carbon Electrodes—Analysis of Waters, Tobacco Cells and Fish Tissues

    PubMed Central

    Krizkova, Sona; Krystofova, Olga; Trnkova, Libuse; Hubalek, Jaromir; Adam, Vojtech; Beklova, Miroslava; Horna, Ales; Havel, Ladislav; Kizek, Rene

    2009-01-01

    We used carbon paste electrodes and a standard potentiostat to detect silver ions. The detection limit (3 Signal/Noise ratio) was estimated as 0.5 μM. A standard electrochemical instrument microanalysis of silver(I) ions was suggested. As a working electrode a carbon tip (1 mL) or carbon pencil was used. Limits of detection estimated by dilution of a standard were 1 (carbon tip) or 10 nM (carbon pencil). Further we employed flow injection analysis coupled with carbon tip to detect silver(I) ions released in various beverages and mineral waters. During first, second and third week the amount of silver(I) ions releasing into water samples was under the detection limit of the technique used for their quantification. At the end of a thirteen weeks long experiment the content of silver(I) ions was several times higher compared to the beginning of release detected in the third week and was on the order of tens of nanomoles. In subsequent experiments the influence of silver(I) ions (0, 5 and 10 μM) on a plant model system (tobacco BY-2 cells) during a four-day exposition was investigated. Silver(I) ions were highly toxic to the cells, which was revealed by a double staining viability assay. Moreover we investigated the effect of silver(I) ions (0, 0.3, 0.6, 1.2 and 2.5 μM) on guppies (Poecilia reticulata). Content of Ag(I) increased with increasing time of the treatment and applied concentrations in fish tissues. It can be concluded that a carbon tip or carbon pencil coupled with a miniaturized potentiostat can be used for detection of silver(I) ions in environmental samples and thus represents a small, portable, low cost and easy-to-use instrument for such purposes. PMID:22399980

  5. Electrodic voltages in the presence of dissolved sulfide: Implications for monitoring natural microbial activity

    SciTech Connect

    Slater, L.; Ntarlagiannis, D.; Yee, N.; O'Brien, M.; Zhang, C.; Williams, K. H.

    2008-10-01

    There is growing interest in the development of new monitoring strategies for obtaining spatially extensive data diagnostic of microbial processes occurring in the earth. Open-circuit potentials arising from variable redox conditions in the fluid local-to-electrode surfaces (electrodic potentials) were recorded for a pair of silver-silver chloride electrodes in a column experiment, whereby a natural wetland soil containing a known community of sulfate reducers was continuously fed with a sulfate-rich nutrient medium. Measurements were made between five electrodes equally spaced along the column and a reference electrode placed on the column inflow. The presence of a sulfate reducing microbial population, coupled with observations of decreasing sulfate levels, formation of black precipitate (likely iron sulfide),elevated solid phase sulfide, and a characteristic sulfurous smell, suggest microbial-driven sulfate reduction (sulfide generation) in our column. Based on the known sensitivity of a silver electrode to dissolved sulfide concentration, we interpret the electrodic potentials approaching 700 mV recorded in this experiment as an indicator of the bisulfide (HS-) concentration gradients in the column. The measurement of the spatial and temporal variation in these electrodic potentials provides a simple and rapid method for monitoring patterns of relative HS- concentration that are indicative of the activity of sulfate-reducing bacteria. Our measurements have implications both for the autonomous monitoring of anaerobic microbial processes in the subsurface and the performance of self-potential electrodes, where it is critical to isolate, and perhaps quantify, electrochemical interfaces contributing to observed potentials.

  6. Uncharged positive electrode composition

    DOEpatents

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  7. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  8. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  9. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1985-01-01

    The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

  10. Bioselective Membrane Electrode Probes

    NASA Astrophysics Data System (ADS)

    Rechnitz, Garry A.

    1981-10-01

    The use of intact bacterial cells or tissue slices of plant and animal origin as immobilized biocatalysts has extended the possible range of potentiometric bioselective membrane electrodes beyond that of conventional enzyme electrodes. The use of such materials as biocatalysts offers advantages in situations where isolated enzymes are not available or where multistep reaction paths are required. The resulting bioselective electrodes also offer exceptional ease of preparation, time stability, and low cost.

  11. Nanoscopic electrode molecular probes

    DOEpatents

    Krstic, Predrag S.; Meunier, Vincent

    2012-05-22

    The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

  12. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, Gordon F. (Inventor)

    1982-01-01

    A low-noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free-ranging subject. The electrode comprises a pocket-shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  13. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, G. F. (Inventor)

    1980-01-01

    A low noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free ranging subject is described. The electrode comprises a pocket shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member, remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  14. Effect of Inner Electrode on Electrical Properties of (Zn,Mg)TiO3-Based Multilayer Ceramic Capacitor

    NASA Astrophysics Data System (ADS)

    Lee, Wen-His; Su, Chi-Yi; Huang, Cheng-Liang; Lee, Ying-Chieh; Hu, Ching-Li; Yang, Jackey; Yang, Tong; Lin, Shih-Pin

    2005-12-01

    In this study, different proportions of silver-palladium alloy used as an inner electrode are adopted to fabricate (Zn,Mg)TiO3-based multilayer ceramic capacitors. Effects of sintering temperature, and measuring frequency on the dielectric properties of the samples with different proportions of the Pd-Ag inner electrode are investigated. The continuity of the inner electrode and the proportion of Pd-Ag of the inner electrode of samples sintered at different temperatures play important roles in determining the dielectric properties.

  15. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  16. Influence of surface properties on the structure of granular silver films and excitation of localized plasmons

    NASA Astrophysics Data System (ADS)

    Shcherbinin, D. P.; Konshina, E. A.; Polischuk, V. A.

    2016-04-01

    Granular silver films deposited on a thin insulating film of amorphous hydrogenated carbon ( a-C:H) and transparent conducting electrode (polycrystalline indium tin oxide (ITO) layer) have been investigated by spectroscopy and microscopy methods. The extinction spectra of silver films on the surface of these materials are found to be significantly different. An annealing of silver films causes a blue shift of the peak of plasmon resonance band in the spectrum of silver nanoparticles: by 16 nm on the a-C:H surface and by 94 nm on the ITO surface. Silver films on the surface of a-C:H films are characterized by a narrower band in the extinction spectrum, which is peaked at 446 nm. The changes observed in the optical density of Ag films are related to the change in size and area of nanoparticles. The results of spectral studies of Ag films are in agreement with the data on the nanostructure obtained by scanning electron microscopy and statistical image processing. The spectra of granular silver films are shown to correlate well with the nanoparticle distribution function over the film area.

  17. Diffractive optical element embedded in silver-doped nanocomposite glass.

    PubMed

    Fleming, Lauren A H; Wackerow, Stefan; Hourd, Andrew C; Gillespie, W Allan; Seifert, Gerhard; Abdolvand, Amin

    2012-09-24

    A diffractive optical element is fabricated with relative ease in a glass containing spherical silver nanoparticles 30 to 40 nm in diameter and embedded in a surface layer of thickness ~10 μm. The nanocomposite was sandwiched between a mesh metallic electrode with a lattice constant 2 μm, facing the nanoparticle containing layer and acting as an anode, and a flat metal electrode as cathode. Applying moderate direct current electric potentials of 0.4 kV and 0.6 kV at an elevated temperature of 200 °C for 30 minutes across the nanocomposites led to the formation of a periodic array of embedded structures of metallic nanoparticles. The current-time dynamics of the structuring processes, optical analyses of the structured nanocomposites and diffraction pattern of one such fabricated element are presented. PMID:23037407

  18. Silver Nafion for Thermogalvanic Applications

    NASA Astrophysics Data System (ADS)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  19. Performance and electrochemical behavior of fluidized bed electrodes

    SciTech Connect

    Huh, T.

    1985-01-01

    The fluidized bed electrode was studied to characterize its behavior and evaluate its possible application to the electrowinning of precious metals and to the energy storage systems. Its performance and electrochemical behavior were analyzed in terms of various operating parameters. The first part of the study is concerned mainly with the overall performance of a fluidized-bed electrode for silver recovery from aqueous cyanide solution. The effects of applied current density, bed expansion, and electrode materials were considered, and its was found that the performance is free of operating problems and is superior to the Azadra-type cell, which is commonly used for precious metal recovery. The second part is concerned with the internal behavior of the fluidized bed electrode. The particle and electrolyte potentials and overpotentials in fluidized bed electrodes of two different types have been measured and analyzed by means of the probability density distribution and the power spectral density distribution. The resistance of such electrodes are also measured. The potential transients are observed to depend on current, bed expansion, and position in the bed (for copper particles) and each potential can be regarded as a time averaged value onto which two kinds of noise, low-frequency flicker noise and white noise, are added.

  20. Electrode loading effect and high temperature performance of ZnO thin film ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Zhou, X. S.; Zhang, J.; Hou, R.; Zhao, C.; Kirk, K. J.; Hutson, D.; Hu, P. A.; Peng, S. M.; Zu, X. T.; Fu, Y. Q.

    2014-10-01

    Nanocrystalline ZnO films of 5.8 μm thick were sputter-deposited on ferritic carbon steel plates (25 × 25 × 3 mm3) and characterized for use as ultrasonic transducers at both room temperature and high temperatures. Electrode loading effects have been studied using two types of electrodes, i.e., sputtered Cr/Au (5/50 nm) and silver paste, with electrode diameters 0.7-2.5 mm. Longitudinal and transverse waves were obtained in pulse-echo tests using both types of electrodes. With a silver paste top electrode, a dominant longitudinal mode was obtained, but with a thin Cr/Au film as the top electrode, shear waves were more dominant. Pulse-echo tests of the ZnO transducers were also performed at elevated temperatures up to 450 °C using a carbon paste electrodes. The sputtered ZnO films maintained a stable crystalline structure and orientation at the elevated temperatures, and ZnO devices on ferritic carbon steel could be used successfully up to 400 °C. However, when the temperature was increased further, rapid surface oxidation of the ferritic carbon steel caused the failure of the transducer.

  1. Membrane Bioprobe Electrodes

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  2. Long term flight electrodes

    NASA Technical Reports Server (NTRS)

    Mosier, B.

    1975-01-01

    The reproducibility, stability, and methods of preparation for the various types and forms of biomedical electrodes are discussed. A critical and selective compilation of information on biological and/or physiological electrodes is presented. A discussion of plant hydrocolloids, clays, hydrophyllic colloids, synthetic waxes, and acrylic polymers is included.

  3. Disposable biomedical electrode

    NASA Technical Reports Server (NTRS)

    Frost, J. D., Jr.; Hillman, C. E., Jr.

    1977-01-01

    Reusable recording cap equipped with compressible snap-on bioelectronic electrodes is worn by patient to allow remote monitoring of electroencephalogram and electro-oculogram waveforms. Electrodes can be attached to inside surface of stretch-textile cap at twelve monitoring positions and at one or two ground positions.

  4. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W.; Harnett, Cindy K.; Rognlien, Judith L.

    2006-08-22

    An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

  5. HIGH VOLTAGE ELECTRODES

    DOEpatents

    Murray, J.J.

    1963-04-23

    S>This patent relates to electrode structure for creating an intense direct current electric field which may have a field strength of the order of two to three times that heretofore obtained, with automatic suppression of arcing. The positive electrode is a conventional conductive material such as copper while the negative electrode is made from a special material having a resistivity greater than that of good conductors and less than that of good insulators. When an incipient arc occurs, the moderate resistivity of the negative electrode causes a momentary, localized decrease in the electric field intensity, thus suppressing the flow of electrons and avoiding arcing. Heated glass may be utilized for the negative electrode, since it provides the desired combination of resistivity, capacity, dielectric strength, mechani-cal strength, and thermal stability. (AEC)

  6. Bifunctional catalytic electrode

    NASA Technical Reports Server (NTRS)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  7. Determination of nicotine by surface-enhanced Raman scattering (SERS)

    SciTech Connect

    Barber, T.E.; List, M.S.; Haas, J.W. III; Wachter, E.A. )

    1994-11-01

    The analytical application of surface-enhanced Raman spectroscopy (SERS) to the determination of nicotine is demonstrated. A simple spectroelectrochemical method using a copper or silver electrode as the SERS substrate has been developed, consisting of three steps: polishing a working electrode to a mirror finish; roughening the electrode in an electrolyte solution; and, finally, depositing the nicotine analyte onto the roughened electrode after immersion in a sample solution. During the reduction cycle, a large enhancement in nicotine Raman scattering is observed at the electrode surface. The intensity of the SERS signal on a silver electrode is linear with concentration from 10 to 900 ppb, with an estimated detection limit of 7 ppb. The total analysis time per sample is approximately five minutes. This procedure has been used to analyze the extract from a cigarette side-stream smoke sample (environmental tobacco smoke); the SERS results agree well with those of conventional gas chromatographic analysis.

  8. Local heat/mass transfer and pressure drop in a two-pass rib-roughened channel for turbine airfoil cooling

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Chandra, P. R.

    1987-01-01

    The heat transfer characteristics of turbulent air flow in a multipass channel were studied via the naphthalene sublimation technique. The naphthalene-coated test section, consisting of two straight, square channels joined by a 180 deg turn, resembled the internal cooling passages of gas turbine airfoils. The top and bottom surfaces of the test channel were roughened by rib turbulators. The rib height-to-hydraulic diameter ratio (e/D) were 0.063 and 0.094, and the rib pitch-to-height ratio (P/e) were 10 and 20. The local heat/mass transfer coefficients on the roughened top wall and on the smooth divider and side walls of the test channel were determined for three Reynolds numbers of 15, 30, and 60, thousand, and for three angles of attack (alpha) of 90, 60, and 45 deg. Results showed that the local Sherwood numbers on the ribbed walls were 1.5 to 6.5 times those for a fully developed flow in a smooth square duct. The average ribbed-wall Sherwood numbers were 2.5 to 3.5 times higher than the fully developed values, depending on the rib angle of attack and the Reynolds number. The results also indicated that, before the turn, the heat/mass transfer coefficients in the cases of alpha = 60 and 45 deg were higher than those in the case of alpha=90 deg. However, after the turn, the heat/mass transfer coefficients in the oblique-rib cases were lower than those in the transverse rib case. Correlations for the average Sherwood number ratios for individual channel surfaces and for the overall Sherwood number ratios are reported. Correlations for the fully developed friction factors and for the loss coefficients are also provided.

  9. Spontaneous self-welding of silver nanowire networks.

    PubMed

    Seong, Baekhoon; Chae, Ilkyeong; Lee, Hyungdong; Nguyen, Vu Dat; Byun, Doyoung

    2015-03-28

    As an alternative to the traditional indium tin oxide transparent electrode, solution-processed metal nanowire thin film has been a promising candidate due to its flexibility. However, high contact resistance between the nanowires remains a major challenge to improve the performance. Here, we have investigated a one-step process of coating and welding of nanowires on flexible film. An electric field-assisted spray coating method developed in this study could generate finely charged droplets of nanowire solution at high flow rate. While charged droplets deposited on the flexible film, electric charges were flowing through the nanowire network producing electrical current. It induced Joule heating and welding at junctions of the nanowires without post-processing steps. Using the coating method, the silver nanowire thin film could be uniformly deposited evenly on a large area substrate, and spontaneously self-welding was carried out between the nanowire networks. The transparent electrode of the silver nanowire prepared by the concurrent deposition and the self-welding process could improve uniformity, roughness and sheet resistance. PMID:25714503

  10. Biopolymer protected silver nanoparticles on the support of carbon nanotube as interface for electrocatalytic applications

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M.; Kumar, V. Sunil; Gobi, K. Vengatajalabathy

    2016-04-01

    In this research, silver nanoparticles (SNPs) are prepared on the surface of carbon nanotubes via chitosan, a biopolymer linkage. Here chitosan act as stabilizing agent for nanoparticles and forms a network on the surface of carbon nanotubes. Synthesized silver nanoparticles-MWCNT hybrid composite is characterized by UV-Visible spectroscopy, XRD analysis, and FESEM with EDS to evaluate the structural and chemical properties of the nanocomposite. The electrocatalytic activity of the fabricated SNP-MWCNT hybrid modified glassy carbon electrode has been evaluated by cyclic voltammetry and electrochemical impedance analysis. The silver nanoparticles are of size ˜35 nm and are well distributed on the surface of carbon nanotubes with chitosan linkage. The prepared nanocomposite shows efficient electrocatalytic properties with high active surface area and excellent electron transfer behaviour.

  11. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity.

    PubMed

    Saugo, M; Flamini, D O; Brugnoni, L I; Saidman, S B

    2015-11-01

    The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus. PMID:26249570

  12. Studying the Performance of Conductive Polymer Films as Textile Electrodes for Electrical Bioimpedance Measurements

    NASA Astrophysics Data System (ADS)

    Cunico, F. J.; Marquez, J. C.; Hilke, H.; Skrifvars, M.; Seoane, F.

    2013-04-01

    With the goal of finding novel biocompatible materials suitable to replace silver in the manufacturing of textile electrodes for medical applications of electrical bioimpedance spectroscopy, three different polymeric materials have been investigated. Films have been prepared from different polymeric materials and custom bracelets have been confectioned with them. Tetrapolar total right side electrical bioimpedance spectroscopy (EBIS) measurements have been performed with polymer and with standard gel electrodes. The performance of the polymer films was compared against the performance of the gel electrodes. The results indicated that only the polypropylene 1380 could produce EBIS measurements but remarkably tainted with high frequency artefacts. The influence of the electrode mismatch, stray capacitances and large electrode polarization impedance are unclear and they need to be clarified with further studies. If sensorized garments could be made with such biocompatible polymeric materials the burden of considering textrodes class III devices could be avoided.

  13. Theoretical investigations of silver clusters and silver-ligand systems.

    SciTech Connect

    Jellinek, J.; Salian, U.; Srinivas, S.

    1999-05-19

    Studies directed at understanding structural and electronic properties of silver clusters have been and remain the subject of an active theoretical [1-22] and experimental [23- 38] effort. One of the reasons is the (still) important role these systems play in the photographic process. Investigations of interactions of silver clusters with different atoms and molecules are motivated primarily by a possible utility of these clusters in catalytic processes. The important role of silver in the selective oxidation of ethylene into ethylene oxide, the feedstock for polyester production, is well-known [39]. Possible variations in chemical reactivity with the cluster size and understanding of the mechanisms of interactions with different ligands may lead to new and more efficient applications. Investigations of cluster-ligand systems also contribute a great deal to a better understanding of gas-surface interactions. Accordingly, theoretical studies of silver clusters and cluster-ligand systems [40-44] fall into two categories--those that use clusters as models for silver surfaces [40], and those that target clusters and cluster-ligand interactions as subjects in their own right [41-44]. The common goal of all these studies is to elucidate the nature of the interatomic interactions and bonding at the microscopic level and thereby arrive at a fundamental understanding and description of the various structural and electronic properties.

  14. Electrodes for sealed secondary batteries

    NASA Technical Reports Server (NTRS)

    Boies, D. B.; Child, F. T.

    1972-01-01

    Self-supporting membrane electrode structures, in which active ingredients and graphite are incorporated in a polymeric matrix, improve performance of electrodes in miniature, sealed, alkaline storage batteries.

  15. Layered electrode for electrochemical cells

    DOEpatents

    Swathirajan, Swathy; Mikhail, Youssef M.

    2001-01-01

    There is provided an electrode structure comprising a current collector sheet and first and second layers of electrode material. Together, the layers improve catalyst utilization and water management.

  16. Measuring electrode assembly

    DOEpatents

    Bordenick, J.E.

    1988-04-26

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture. 2 figs.

  17. Measuring electrode assembly

    DOEpatents

    Bordenick, John E.

    1989-01-01

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture.

  18. Development of silver-zinc cells of improved cycle life and energy density

    NASA Astrophysics Data System (ADS)

    Serenyi, Roberto; James, Stanley D.

    1994-03-01

    Substantial increases in the cost effectiveness and range of naval underwater vehicles are possible by virtue of advances made, in this program, to silver-zinc, vehicle propulsion batteries. To improve battery cycle life and energy density, electropermeable membranes (EPM's) were used as additives and/or as coatings for the negative electrodes and as coatings for conventional separator materials. Also, bismuth oxide was tested as an additive to the negative electrodes and P2291-40/20, a radiation-grafted polyethylene film, as a separator used in conjunction with silver-treated cellophane. EPM's used as negative electrode additives and also as coatings for Celgard 2500 microporous polypropylene greatly improved cells. Cells with EPM's used as coatings for the negative electrodes failed rapidly because of an error in formulation. Cells with 10 percent bismuth oxide in the negative electrodes exhibited substantially lower capacity than the standard cells and were removed from the test. Cells with radiation-grafted polyethylene separators provided fewer cycles than the standard cells, with 5 percent higher capacity and 6 percent lower utilization of active materials by cycle 60. However, the slightly better capacity of these cells, realized due to the additional space available for active materials, does not compensate for their generally unimpressive performance.

  19. Development of a silver/polymer nanocomposite interconnection layer for organic tandem solar cells

    NASA Astrophysics Data System (ADS)

    Torabi, Naeimeh; Behjat, Abbas; Shahpari, Mahboobeh; Edalati, Shadi

    2015-01-01

    Interconnecting layers (ICL) play an important role in regulating the performance of tandem devices. We report the design of a solution-processed ICL that consists of a silver/polymer nanocomposite deposited on the top of a TiO2 layer. This nanocomposite contains modified poly (3,4-ethylenedioxythiophene) polystyrene sulfonic acid (PEDOT:PSS), and silver nanoparticles (Ag NPs) synthesized by the chemical reduction of silver nitrate in the presence of PEDOT:PSS. Formation of Ag NPs was confirmed by monitoring the plasmon absorption peak characteristics in the UV-visible spectrum of the synthesized nanocomposite. Transmission electron microscopy analysis indicated the presence of spherical silver NPs in a polymer matrix with a mean size of around 20 nm. The sheet resistance of PEDOT:PSS was found to be 2474±35 Ω/sq. It was changed to 445±28 Ω/sq after solvent modification and decreased to 53.31±3.59 Ω/sq after synthesizing silver NPs in the polymer medium. Meanwhile, the transparency of the nanocomposite film deposited on TiO2 was 89.6%, which is considered appropriate for an interconnecting electrode. We demonstrated that by incorporating a silver/polymer nanocomposite as a hole-transporting layer in contact with TiO2 as an electron-transporting layer, the ohmic behavior of ICL is enhanced with respect to pristine PEDOT:PSS. P3HT:PCBM-based tandem solar cells based on this solution-processed intermediate electrode represent significantly increased open-circuit voltage (Voc), reaching close to the sum of the single cells. By incorporating the nanocomposite in the tandem structure, a Voc of 1.1 V was obtained. This value was almost the sum of the Voc of two single cells, which was 1.18 V.

  20. Impact of effective volume ratio of a dispersant to silver nano-particles on silicon solar cell efficiency in direct ink-jet metallization

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Youn; Cha, Yong-Kee; Ryu, Han-Hee; Kim, Sang-Ho

    2012-11-01

    In this study, the direct ink-jet metallization of finger electrodes on a multi-crystalline silicon solar cell is attempted and the impact of the silver particle size on solar cell efficiency is investigated using silver nano-inks with two different silver particle sizes. When the silver particle size approaches the nano-metric regime of around 18.1 nm, the solar cell efficiency is as low as 8.6%. On the other hand, the solar cell efficiency increases up to a maximum of 12.1% using silver particles that are around 180 nm in size. It is found that the dependence of the solar cell efficiency on the silver particle size is related to the effective volume ratio of a dispersant to silver. As the effective volume ratio increases, detrimental effects, such as an explosive decomposition of the dispersant and high residual stress due to the high volumetric shrinkage of a direct ink-jet printed finger electrode, result in poor contact formation which eventually leads to poor solar cell efficiency. With these experimental results, potential development directions for an ink-jet printer for the direct metallization of a silicon solar cell are comprehensively discussed.

  1. Multifunctional reference electrode

    DOEpatents

    Redey, L.; Vissers, D.R.

    1981-12-30

    A multifunctional, low mass reference electrode of a nickel tube, thermocouple means inside the nickel tube electrically insulated therefrom for measuring the temperature thereof, a housing surrounding the nickel tube, an electrolyte having a fixed sulfide ion activity between the housing and the outer surface of the nickel tube forming the nickel/nickel sulfide/sulfide half-cell are described. An ion diffusion barrier is associated with the housing in contact with the electrolyte. Also disclosed is a cell using the reference electrode to measure characteristics of a working electrode.

  2. Multifunctional reference electrode

    DOEpatents

    Redey, Laszlo; Vissers, Donald R.

    1983-01-01

    A multifunctional, low mass reference electrode of a nickel tube, thermocouple means inside the nickel tube electrically insulated therefrom for measuring the temperature thereof, a housing surrounding the nickel tube, an electrolyte having a fixed sulfide ion activity between the housing and the outer surface of the nickel tube forming the nickel/nickel sulfide/sulfide half-cell. An ion diffusion barrier is associated with the housing in contact with the electrolyte. Also disclosed is a cell using the reference electrode to measure characteristics of a working electrode.

  3. Field-assisted patterned dissolution of silver nanoparticles in phosphate glass

    SciTech Connect

    Andreyuk, A. Albert, J.

    2014-09-21

    Phosphate glass samples doped with silver ions through a Na⁺-Ag⁺ ion-exchange process were treated in a hydrogen atmosphere at temperatures near 430°C for durations ranging from 4 to 5 h. Such treatment causes metallic silver precipitation at the surface as well as nanoclustering of silver atoms under the surface under conditions very similar to those used for silicate glasses. The presence of silver clusters resulted in a characteristic coloring of the glass and was verified by the observation of a plasmon resonance peak near 410–420 nm in the absorption spectra. Applying a DC voltage between 1.4 and 2 kV at temperatures between 120 and 130°C led to dissolution of the clusters in the area under the positive electrode, thereby bleaching the glass color. The use of a patterned doped-silicon electrode further led to the formation of a 300 nm thick surface relief on the glass surface and of a volume complex permittivity grating extending at least 4 μm under the surface. Such volume complex refractive index gratings may find applications in passive or active (laser) photonic devices in rare-earth doped phosphate glasses, where conventional bulk grating formation techniques have limited applicability.

  4. Field-assisted patterned dissolution of silver nanoparticles in phosphate glass

    NASA Astrophysics Data System (ADS)

    Andreyuk, A.; Albert, J.

    2014-09-01

    Phosphate glass samples doped with silver ions through a Na+-Ag+ ion-exchange process were treated in a hydrogen atmosphere at temperatures near 430 °C for durations ranging from 4 to 5 h. Such treatment causes metallic silver precipitation at the surface as well as nanoclustering of silver atoms under the surface under conditions very similar to those used for silicate glasses. The presence of silver clusters resulted in a characteristic coloring of the glass and was verified by the observation of a plasmon resonance peak near 410-420 nm in the absorption spectra. Applying a DC voltage between 1.4 and 2 kV at temperatures between 120 and 130 °C led to dissolution of the clusters in the area under the positive electrode, thereby bleaching the glass color. The use of a patterned doped-silicon electrode further led to the formation of a 300 nm thick surface relief on the glass surface and of a volume complex permittivity grating extending at least 4 μm under the surface. Such volume complex refractive index gratings may find applications in passive or active (laser) photonic devices in rare-earth doped phosphate glasses, where conventional bulk grating formation techniques have limited applicability.

  5. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with ferrous... certification. Certification of this color additive is not necessary for the protection of the public health...

  6. Cuff electrodes for very small diameter nerves -- prototyping and first recordings in vivo.

    PubMed

    Ordonez, Juan S; Pikov, Victor; Wiggins, Harvey; Patten, Craig; Stieglitz, Thomas; Rickert, J; Schuettler, Martin

    2014-01-01

    A fabrication method for cuff electrodes to interface small nerves was developed. Medical grade silicone rubber conforms the body of the cuff and insulation of the wires, platinum was used as metal for the embedded wiring and contacts. Planar electrode arrays where fabricated using a picosecond laser and then positioned into a carrying tube to provide the third dimension with the desired inner diameter (Ø 0.3-0.5 mm). The post preparation of the cuffs after structuring allows the fabrication of a stable self-closing flap that insulates the opening slit of the cuff without the need of extra sutures. Basic for the success of the cuff is the laser-based local thinning of both the silicone rubber and the metal at defined sections. This is critical to permit the PDMS' body to dominate the mechanical properties. Finite element modeling was applied to optimize the displacement ability of the cuff, leading to design capable of withstanding multiple implantation procedures without wire damage. Furthermore, the contact's surface was roughened by laser patterning to increase the charge injection capacity of Pt to 285 μC/cm(2) measured by voltage transient detection during pulse testing. The cuff electrodes were placed on a small sympathetic nerve of an adult female Sprague-Dawley rat for recording of spontaneous and evoked neural activity in vivo. PMID:25571569

  7. Thin-film zinc/manganese dioxide electrodes based on microporous polymer foils

    NASA Astrophysics Data System (ADS)

    Barbic, P. A.; Binder, L.; Voss, S.; Hofer, F.; Grogger, W.

    Thin-film electrodes allow manufacturing of flat batteries of variable design which can be used for the development of smaller electric appliances. Substituting the metal carrier by conductive plastics leads to a considerable reduction of battery weight. Usually the electroactive materials are deposited onto the surface of the carrier. A significant improvement of the originally poor adherence between polymer foil and electroactive layers can be achieved by mechanical (surface roughening) or chemical (etching) pretreatment. Another way to form extremely thin electrodes having a thickness in the range of some ten micrometers is reported here. First, a metallic layer is deposited onto one surface of a 25 μm thin porous polypropylene foil. Subsequently, the electroactive materials are electrolytically deposited into the pores of the metallized foil providing the required conductive connection through the plastic matrix by themselves. In this case the flexibility of the polymer has a positive influence on the problem of volume change of manganese dioxide during charging and discharging, respectively, because the plastic provides flexible `mechanical struts' which act as a `binder' and therefore prevent increasing internal resistance due to contact problems. Assembling a zinc filled polymer and a manganese dioxide filled one in such a way that both metallic back-layers are in contact, a thin bipolar zinc/manganese dioxide electrode can be obtained.

  8. Wearable multifunctional sensors using printed stretchable conductors made of silver nanowires

    NASA Astrophysics Data System (ADS)

    Yao, Shanshan; Zhu, Yong

    2014-01-01

    Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ~1.2 MPa) and finger touch with high sensitivity, fast response time (~40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels.Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ~1.2 MPa) and finger touch with high sensitivity, fast response time (~40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels. Electronic

  9. Heat-sterilized silver oxide-zinc cells: Cycle life studies

    NASA Technical Reports Server (NTRS)

    Arms, J. T.

    1973-01-01

    A JPL study was conducted to evaluate the cell design parameters that contribute to the cycle life of sealed, heat-sterilized silver oxide-zinc cells. Test cells having a rated capacity of 4.2 A-h were fabricated using zinc oxide electrodes prepared by the sintered Teflon process. Two separator variations were evaluated, one having acrylic acid and the other methacrylic acid grafted to irradiated polyethylene film. Significant results of this study include the following: (1) cycle life in excess of 300 cycles was attained; (2) a zinc oxide/silver stoichiometric ratio of 1.5 resulted in greater cycle life than a ratio of 1.1, and similar cycle life to cells having a ratio of 2; (3) cells having methacrylic acid grafted separators suffered somewhat less in capacity loss due to zinc electrode shape change than cells having acrylic acid type; (4) use of acrylic acid grafted separators was slightly superior to the methacrylic acid type in respect to silver penetration; and (5) the inclusion of a layer of potassium titanate paper adjacent to the zinc electrodes resulted in cells that achieved higher cycle life before any of the group failed than that reached by cells of any other construction.

  10. Improved capacitive EKG electrode

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Griffith, M. E.; Portnox, W. M.; Stotts, L. J.

    1979-01-01

    Light, compact electrode monitors heart signals through burn ointment and requires no electrolyte paste for coupling to skin. Innovation is useful because of its ability to monitor heart condition of burn victims.

  11. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity...

  12. Fluorescent silver nanoclusters stabilized by DNA scaffolds.

    PubMed

    Yuan, Zhiqin; Chen, Ying-Chieh; Li, Hung-Wen; Chang, Huan-Tsung

    2014-09-01

    Fluorescent silver nanoclusters, in particular DNA stabilized (templated) silver nanoclusters, have attracted much attention because of their molecule-like optical properties, strong fluorescence and good biocompatibility. In this feature article, we summarize the DNA stabilized silver nanoclusters from the viewpoints of synthesis, optical properties, as well as recent applications in biological detection and imaging. PMID:24901353

  13. The Myth of the Silver Surfer

    ERIC Educational Resources Information Center

    Gorard, Stephen; Selwyn, Neil

    2008-01-01

    In this article, the authors write about the myth of the "silver surfers"--those third-age learners adept at using the internet and other technologies for a mixture of formal and informal learning episodes. The notion of the silver surfer has endured since the latter half of the 1990s. It is sustained by the annual Silver Surfer week, media…

  14. Self-assembled silver nanochains for surface-enhanced Raman scattering.

    PubMed

    Yang, Yong; Shi, Jianlin; Tanaka, Taiki; Nogami, Masayuki

    2007-11-20

    Surface-enhanced Raman scattering (SERS) integrates high levels of sensitivity with spectroscopic precision and has tremendous potential for chemical and biomolecular sensing. The key to the wider application of Raman spectroscopy using roughened metallic surfaces is the development of highly enhancing substrates for analytical purposes. Here, we demonstrate a simple strategy for self-assembling silver nanochains on glass substrates for sensitive SERS substrates. The chain length of short Ag nanochains can be controlled by adjusting the concentration of cetyltrimethylammonium bromide (CTAB) and 11-mercaptoundecanoic acid (MUA). CTAB with appropriate concentration serves as the "glue" that can link the {100} facets of two neighboring Ag nanoparticles. MUA is found to be effective in "freezing up" the aggregation of Ag short chains and preventing them from further aggregating into a long chainlike network structure. The surface plasmon bands can be tuned over an extended wavelength range by controlling the length of the nanochains. The Ag monolayer, mainly composed of four-particle nanochains, exhibited the maximum SERS enhancement factor of around 2.6 x 108, indicating that a stronger SERS enhancement can be obtained in these interstitial sites of chainlike aggregated Ag nanoparticles. PMID:17963408

  15. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-15

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  16. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-01

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  17. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

    A durable multilayer mirror includes reflective layers of aluminum and silver and has high reflectance over a broad spectral range from ultraviolet to visible to infrared. An adhesion layer of a nickel and/or chromium alloy or nitride is deposited on an aluminum surface, and a thin layer of silver is then deposited on the adhesion layer. The silver layer is protected by a passivation layer of a nickel and/or chromium alloy or nitride and by one or more durability layers made of metal oxides and typically a first layer of metal nitride. The durability layers may include a composite silicon aluminum nitride and an oxinitride transition layer to improve bonding between nitride and oxide layers.

  18. Photonic Flash Sintering of Ink-Jet-Printed Back Electrodes for Organic Photovoltaic Applications.

    PubMed

    Polino, Giuseppina; Shanmugam, Santhosh; Bex, Guy J P; Abbel, Robert; Brunetti, Francesca; Di Carlo, Aldo; Andriessen, Ronn; Galagan, Yulia

    2016-01-27

    A study of the photonic flash sintering of a silver nanoparticle ink printed as the back electrode for organic solar cells is presented. A number of sintering settings with different intensities and pulse durations have been tested on both full-area and grid-based silver electrodes, using the complete emission spectrum of the flash lamps from UV-A to NIR. However, none of these settings was able to produce functional devices with performances comparable to those of reference cells prepared using thermally sintered ink. Different degradation mechanisms were detected in the devices with a flash-sintered back electrode. The P3HT:PCBM photoactive layer appears to be highly heat-sensitive and turned out to be severely damaged by the high temperatures generated in the silver layer during the sintering. In addition, UV-induced photochemical degradation of the functional materials was identified as another possible source of performance deterioration in the devices with grid-based electrodes. Reducing the light intensity does not provide a proper solution because in this case the Ag electrode is not sintered sufficiently. For both types of devices, with full-area and grid-based electrodes, these problems could be solved by excluding the short wavelength contribution from the flash light spectrum using a filter. Optimized sintering parameters allowed manufacture of OPV devices with performance equal to those of the reference devices. Photonic flash sintering of the top electrode in organic solar cells was demonstrated for the first time. It reveals the great potential of this sintering method for the future roll-to-roll manufacturing of organic solar cells from solution. PMID:26704172

  19. Techniques of Electrode Fabrication

    NASA Astrophysics Data System (ADS)

    Guo, Liang; Li, Xinyong; Chen, Guohua

    Electrochemical applications using many kinds of electrode materials as an advanced oxidation/reduction technique have been a focus of research by a number of groups during the last two decades. The electrochemical approach has been adopted successfully to develop various environmental applications, mainly including water and wastewater treatment, aqueous system monitoring, and solid surface analysis. In this chapter, a number of methods for the fabrication of film-structured electrode materials were selectively reviewed. Firstly, the thermal decomposition method is briefly described, followed by introducing chemical vapor deposition (CVD) strategy. Especially, much attention was focused on introducing the methods to produce diamond novel film electrode owing to its unique physical and chemical properties. The principle and influence factors of hot filament CVD and plasma enhanced CVD preparation were interpreted by refereeing recent reports. Finally, recent developments that address electro-oxidation/reduction issues and novel electrodes such as nano-electrode and boron-doped diamond electrode (BDD) are presented in the overview.

  20. Electrocatalysts for oxygen electrodes

    SciTech Connect

    Yeager, E. . Dept. of Chemistry Case Western Reserve Univ., Cleveland, OH . Case Center for Electrochemical Sciences)

    1990-10-01

    The overall objective of this research was an in-depth understanding of the factors controlling O{sub 2} reduction and generation on various electrocatalysts and the use of this understanding to identify much higher activity, stable catalysts. The following is a brief summary of the research for the period 1 April 1989 to 31 March 1990. (1) Transition metal monomeric and sheet-polymeric macrocycle catalysts -- The iron tetrasulfonated phthalocyanine (FeTsPc) complex adsorbed on an electrode surface has high activity for the 4-electron reduction of O{sub 2} to water or OH{sup {minus}} in alkaline solutions. (2) Polymer-modified electrodes -- Poly(4-vinyl pyridine) (PVP)-modified electrodes with adsorbed CoTsPc exhibited much higher catalytic activity for O{sub 2} reduction than the electrode with only adsorbed CoTsPc in acid solutions. (3) Transition metal oxide catalysts and bifunctional electrodes -- Anion-exchange membranes were found to greatly improve the performance of the pyrochlore-based bifunctional oxygen electrodes when operating in the O{sub 2} generation mode. (4) Catalyst supports -- The use of mildly fluorinated carbon blacks as catalyst supports for platinum was explored in cooperation with the Electrosynthesis Company (ESC). 23 refs., 28 figs., 7 tabs.