Ionic conductivity of superionic conducting glasses in the pseudobinary system AgIAg2MoO4

The ionic conductivity was measured in the temperature range 250–300 K as a function of composition of superionic conducting glasses in the pseudobinary system AgIAg₂MoO₄. The conductivity, ranging from 10^?2 to 10^?4 Ω^?1 cm^?1 at room temperature, increases linearly in logarithmic scale with increasing AgI content, while the total silver ion concentration remains nearly constant in the whole glass-forming region of the present system. Such a composition dependence of conductivity is considered to be evidence that only a fraction of the silver ions in glass contributes to the ionic conduction. The conductivity and the activation energy for conduction differ slightly between bulk glasses and pressed pellets of pulverized glasses. The close agreement in bulk glasses and pellets suggests that bulk rather than grain boundary or surface diffusion dominates the conduction process in the present glasses.     

Electrochemical behavior of silver thin films interfaced with yttria-stabilized zirconia

Thin silver films (100–800 nm) were deposited by physical vapor deposition (PVD) on yttria-stabilized zirconia solid electrolyte. The electric percolation as a function of the film thickness was studied during deposition and annealing using a two-electrode in-situ resistance measurement technique. Electrical percolation was achieved in as-deposited films greater than 5.4?±?0.4 nm; however, thermal treatment (550 °C in air) resulted in film dewetting for Ag films as thick as 500 nm and formation of electronically isolated Ag nanoparticles, as was confirmed by SEM and XPS. In thermally treated samples, stable electronic conductivity associated with a continuous percolated network was only observed in samples greater than 600 nm in thickness. The effect of polarization on the electrochemical reactions at the three-phase (electrode-gas-electrolyte) and two-phase (electrode-electrolyte) boundaries of the electrode was investigated by solid electrolyte cyclic voltammetry (SECV) at 350 °C and P _O2?=?6 kPa. With the application of positive potential, silver oxide (Ag₂O) was found to form along the three-phase boundary and then extends within the bulk of the electrode with increasing anodic potentials. By changing the hold time at positive potential, passivating oxide layers are formed which results in a shift in favor of the oxygen evolution reaction at the working electrode. This oxide forms according to a logarithmic rate expression with thick oxides being associated with decrease in current efficiency for subsequent oxide formation.     

Doping of processable conducting poly(m‐aminophenol) with silver nanoparticles

Processable poly(m‐aminophenol) (PmAP) was synthesized using ammonium persulfate (APS) oxidant in 0.6 M sodium hydroxide solution at room temperature. Soluble silver hydroxide ammonium complex was formed by dissolving silver nitrate in excess liquor ammonia and the thermal decomposition of this complex easily produced silver nanoparticle. Then, in situ silver nanoparticle‐doped PmAP film was obtained by casting PmAP film from dimethyl sulfoxide (DMSO) with silver hydroxide ammonia complex mixture at 140°C. The nanocomposite was characterized by ultraviolet‐visible spectroscopy, Fourier transformed spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, electron dispersion spectroscopy, thermogravimetric analysis, and X‐ray diffraction analysis. The average size of the nanoparticle was around 130–140 nm as confirmed by the TEM analysis. Synthesized PmAP silver nanocomposite showed the highest DC‐conductivity of 1.03 × 10^?6 S/cm. From the above characterizations, it can be said that silver nanoparticle shows some doping effect on the conductivity of PmAP. The doping level of the silver nanoparticle inside the polymer was optimized in terms of DC‐conductivity of the silver nanoparticle‐doped PmAP film. Copyright © 2009 John Wiley & Sons, Ltd.     

The structure and conductivity of thin composite films formed from nanodispersions of silver particles by the moving meniscus method

The formation processes, structure, geometric parameters, and conductivity are studied for thin composite films prepared from nanodispersions of silver particles with diameters smaller than 10 nm by the moving meniscus method. The thickness and conductivity of the films are determined as functions of the mass concentration of a precursor (AgNO₃) and the concentration (size) of silver nanoparticles. Some of these functions are nonmonotonic. The dependences of the conductivity on these parameters are found to have the character of a percolation transition. Heterogeneous crystallization of soluble components of the colloidal solutions on silver nanoparticles plays an essential role in the formation of the films.     

Preparation of conducting silver paste with Ag nanoparticles prepared by e-beam irradiation

Conducting silver paste was prepared by using Ag nanoparticles which were synthesized by e-beam irradiation method (from KAERI); its conductivity was comparatively determined with Ag nanoparticles which were prepared by thermolysis method (commercial). The silver nanoparticles with the diameter of approximately 150 nm size prepared by e-beam irradiation were mixed with glass frit and sintered for 1 h at 500 °C. It is presumably concluded that the wt% of silver nanoparticle, size distribution and homogenous dispersibility of Ag nanoparticles in the pastes are the critical factors for the high conductivity of the paste. Among the various wt% of silver nanoparticle in the conducting silver pastes, silver paste with 90 wt% of silver nanoparticle has the highest conductivity as 1.6×10⁴ S cm^?1. This conductivity value is 1.6 times higher than the Ag pastes which were prepared with silver nanoparticles obtained by thermolysis method.     

聚苯胺对新型杂化透明导电薄膜制备和性能的影响

以聚苯胺和掺锑的氧化锡作为主要原料, 采用溶胶-凝胶法制备了新型有机-无机杂化透明导电薄膜. 薄膜的可见光透过率为85%以上, 电导率达到10⁰～10¹ S•cm^－1. 研究了聚苯胺含量的变化对浸涂液粘度、薄膜结构、光透过率、电导率的影响. 随着聚苯胺引入量的增加, 薄膜的电导率、可见光透过率均有所增大. 浸涂液的粘度可在长达25天的时间内保持稳定, 很适于浸涂工艺. 扫描电镜照片显示, 薄膜比较致密、均匀, 厚度为250 nm左右.     

Effect of humidity on the conductivity of graphite oxide during its photoreduction

The influence of humidity on the conductivity of graphite oxide (GO) films has been considered. Graphite oxide films of a 200–500 nm thickness become conductors to have a conductivity of 10^?6 to 10^?2 S/cm when humidity increases from 30 to 100%. Film morphology varies during the course of water diffusion. Ultraviolet light-mediated reduction of GO decreases the sensitivity to humidity until its complete disappearance.     

Evolution of crystalline structure in SnS thin films prepared by chemical deposition

Crystal structure and morphology undergo significant evolution in thin films of tin(II) sulfide prepared by chemical deposition, over a narrow interval of bath temperature of 20–40 °C, but has not been recognized in previous studies. The chemical bath is constituted using tin(II) chloride, triethanolamine, ammonia(aq.) and thioacetamide. At bath temperature of 20 °C, the deposition rate of the film is 10 nm/h; and at 24 h, a film of thickness 260 nm is obtained. This film is compact and with a predominantly cubic (Cub-) crystalline structure. At 40 °C, the deposition rate is 25 nm/h, and a film of 600 nm in thickness is deposited in 24 h. However, this film has evolved into vertically stacked platelets of orthorhombic (OR-) crystalline structure. The transition from compact-to-platelet morphology as well as from Cub-to-OR-crystalline structure is observed near a deposition temperature, 35 °C. The Cub-SnS has a characteristic high optical band gap, 1.67 eV (direct gap; forbidden transitions) with an electrical conductivity, 10⁻⁷(Ω cm)⁻¹; both properties being un-affected when films are heated at 300 °C in a nitrogen ambient. In OR-SnS, the band gap is 1.1 eV (indirect gap; allowed transitions). The electrical conductivity of such films is notably higher, 10⁻⁴ (Ω cm)⁻¹, which increases further by an order of magnitude when the films have been heated at 300 °C in nitrogen.     

Preconcentration and electroanalysis of silver at pt electrode modified with poly(2-aminothiazole)

Conducting poly(2-aminothiazole) (PAT) films were electrodeposited on a platinum disc electrode surface by constant potential electrolysis of 2-aminothiazole (AT) for the stripping voltammetric determination of Ag(I). Ag(I) was preconcentrated on the polymer matrix by dipping the modified Pt electrode (PAT-Pt electrode) into Ag(I)(aq) solution. Effects of the film thickness, reduction potential, pH, preconcentration time, Ag(I) concentration and the interference of some other metal ions on the oxidation peak current of silver were studied. Cu(II) interference observed to be significant for the stripping voltammetric determination of Ag(I). The detection limit was calculated on the basis of signal to noise ratio of 3 as 2 × 10^?7 mol L^?1.     

Electrical properties of ion-implanted poly(p-phenylene sulfide)

Ion implantation of impurities into thin films of poly(p-phenylene sulfide) (PPS) is found to increase the conductivity of the material by up to 12 orders of magnitude. The increase is stable under exposure to ambient conditions, in contrast to the instability of the conductivity increases in PPS produced by chemical doping with AsF₅. PPS films 0.1–0.2 μm thick are spin cast from solution onto interdigitated electrodes patterned on an oxidized silicon substrate. The room-temperature interelectrode resistance is measured as a function of implantation fluence. An estimate of film conductivity is obtained from this resistance with a simple model for the electrode and film geometry. A first experiment yielded similar conductivity increases for implantation of either arsenic or krypton. At a fluence of 1 × 10¹⁶cm^?;2, which corresponds to an average impurity concentration of 2.5 × 10²¹cm^?3, the conductivity reaches an apparently saturated value of 1.5 × 10^?5 (Ω cm)^?1. Infrared spectra of the films before and after implantation suggest that crosslinking may be present in the implanted films, and Auger studies show stoichiometric changes throughout the implanted layer. These results suggest that the observed conductivity changes are the result of molecular rearrangements produced by the implantation rather than the result of specific chemical doping. Specific chemical doping may, however, explain the results of a second experiment in which implantation of bromine resulted in substantially larger conductivities found to increase at an approximate linear rate from a value of 1.0 × 10^?4 (Ω cm)^?1 at a fluence of 1 × 10¹⁶ cm^?2 to a value of 4.0 × 10^?4 (Ω cm)^?1 at a fluence of 3.16 × 10¹⁶ cm^?2.     

Dielectric properties of sols of silver nanoparticles capped by alkyl carboxylate ligands

Sols of silver nanoparticles in toluene were studied by broadband dielectric spectroscopy (10⁻³–10⁵ Hz). The frequency dependences of the specific alternating current (ac) conductivity and the complex electric modulus were used to estimate the temperature/frequency intervals of long- and short-range charge transfer occurs, respectively. A considerable increase (by more than 30 °C) in the Vogel temperature T ₀ and the glass transition temperature T _g in sols compared with the pure solvent was found. It can be hypothesized that these cooperative effects reflect the initial stage of the superlattice formation. Although the dielectric characteristics of sols are generally controlled by the conductivity relaxation, the dielectric response was observed in the high-frequency range (1–10³ Hz) at low temperatures (from −50 to +10 °C). This response results from the presence of nanoparticles in solution. It is supposed that the relaxation is caused by the motion of ion impurities on the Ag nanoparticle surface within the carboxylate ligands shell. The dielectric properties of films strongly depend on both the characteristics of nanoparticles and the conditions of the film preparation. Like in sols, the direct current (dc) conductivity and the dielectric response of Ag nanoparticles in films are due to ion impurities.     

Theoretical and experimental analyses of the deposited silver thin films

The silver thin films have been prepared using magnetron DC‐sputtering. We discuss in detail the thin films AFM images and their properties in different sputtering times of 2 to 6 minutes. Despite the low thickness of the films, the roughness saturation amounts, W_s, are well separated. The surface data do not follow the normal Family‐Vicsek scaling, and we have the local growth exponent, β(W_s(t)∼t^β). We obtained the global roughness scaling exponent α=0.36 and growth exponent, β=0.50. We also obtain the fractal spectrum of the data, f(α). The results show that the spectrum is right‐hook like. It distinguishes between different film thicknesses even in small sizes of hundreds of nanometers. Furthermore, we measure the surface conductivities and compare them to the thin film roughnesses. We investigate the roughness and fractality of the AFM data, looking for their relations to width and conductivity of the silver thin film samples.     

Electrical conductivity of hexacene doped with iodine

Hexacene (HEX) and derivatives such as dihydrohexacene and dihydroxyhexcane quinone were synthesized and thin films of them were prepared by the sublimation method. The structure and conductivity of the films both before and after doping with iodine were studied. The doped HEX film showed the conductivity of 3 × 10^?2 S/cm at room temperature, which was lower than expected since the conductivity of highly ordered pentacene was above 100 Ω^?1 cm^?1. The reason for the low conductivity was considered to be the disorder in molecular alignment since the HEX film showed an amorphous structure. A reversible change in the conductivity of the HEX film was observed in air and in vacuum.     

Spectrophotometric determination of silver with 4-(3,5-dibromo-2-pyridylazo)-N,N-diethylaniline in the presence of sodium dodecylsulfate

The bidentate ligands, 4-(3,5-DiBr-PAEA) and 4-(3,5-DiBr-PAESA) react with silver(I) ion to form the Agl2 chelate in the presence of anionic or nonionic surfactant. The molar absorptivity at 600 nm is 80 000 l mol^?1 cm^?1 in 0.1% sodium dodecylsulfate solution. Optimum conditions for the spectrophotometric determination of silver in the range 0.1–1.0 mg l^?1 with 3,5-diBr-PAEA are reported. A flow-injection procedure is also presented.     

ATR-SEIRAS study of the adsorption of acetate anions at chemically deposited silver thin film electrodes

The adsorption of acetate anions at silver thin film electrodes has been studied by in-situ infrared spectroscopy experiments with a Kretschmann internal reflection configuration. Stable silver thin films were chemically deposited on germanium substrates. Ex-situ STM images show mean grain sizes ranging from ca. 20 to 90 nm for deposition times between 2 and 20 min, respectively. The thickness of the silver film, measured by AFM, is typically around 10 nm for a deposition time of 10 min and increases up to 50 nm for a deposition time of 20 min. Roughness factors around 2.3 have been obtained for the silver films from the charge involved in lead underpotential deposition (UPD). A noticeable enhancement of the infrared absorption of adsorbed species (SEIRA effect) is observed when the silver films are used as electrodes under internal total reflection conditions. Maximum intensities of the adsorbate bands were observed for a deposition time of 10 min and an angle of incidence around 65 degrees . The potential-dependent infrared spectra of acetate and interfacial water are consistent with previously proposed models involving the existence of weakly hydrogen-bonded water molecules at potentials below the potential of zero charge and the reorientation of water molecules at potentials above the potential of zero charge. Results reported in this work suggest a weak interaction between acetate and water molecules adsorbed at the silver thin film electrodes.     

Efficient gold and silver electrodes for surface enchanced raman spectral studies of electrochemical systems: The behaviour of pyridine and naphthalene adsorbed on roughened gold electrodes

A method is described whereby surface enhanced Raman (SER) active electrode surfaces of gold and silver may be made without recourse to the oxidation—reduction techniques which have been used hitherto. This method involves electroplating at low current density from dilute (< 10^?2M) solutions of a suitable salt or complex in the absence of supporting electrolyte.Scanning electron microscopy shows the surfaces to consist of small spherical particles of fairly constant diameter packed together on the electrode. The sphere diameters are typically 70 nm (gold) and 180 nm (silver) for electrodes prepared in this manner. These electrodes exhibit intense SER scattering and have advantages over oxidation—reduction roughened electrodes. As examples of their utility some results are presented relating to the gold/pyridine and gold/naphthalene systems and these are discussed in relation to results obtained by other workers in similar systems using different methods, i.e., ellipsometry and differential capacitance variation.     

Solubility studies in aqueous media: I. Solubility product of silver permanganate and standard electrode potentials of silver—silver permanganate electrode in aqueous media

The solubility and solubility product of silver permanganate in water have been determined at the temperatures ranging from 15 to 35°C over 5°C intervals in the presence of an added electrolyte, sodium perchlorate. The solubility of silver permanganate ranges from 0.966 x 10^?5 mol 1^?1 at 15°C to 1.420x10^?5 moll^?1 at 35°C and the corresponding solubility product 0.933 x 10^?10 mol² 1^?2 at 15°C to 2.017 x 10^?10 mol² 1^?2 at 35°C. The standard potentials of the Ag(s)/AgMnO₄(s)/ MnO^?₄ electrode have been calculated at these temperatures. The mean activity coefficients of silver permanganate at various rounded molarities of sodium perchlorate solutions, and the standard thermodynamic quantities for the process AgMnO₄(s)→Ag⁺ (aq)+MnO^?₄(aq) have been calculated at these temperatures.     

Proton Conductivities of Graphene Oxide Nanosheets: Single,Multilayer, and Modified Nanosheets

Proton conductivities of layered solid electrolytes can be improved by minimizing strain along the conduction path. It is shown that the conductivities (σ) of multilayer graphene oxide (GO) films (assembled by the drop‐cast method) are larger than those of single‐layer GO (prepared by either the drop‐cast or the Langmuir‐Blodgett (LB) method). At 60 % relative humidity (RH), the σ value increases from 1×10^?6 S cm^?1 in single‐layer GO to 1×10^?4 and 4×10^?4 S cm^?1 for 60 and 200 nm thick multilayer films, respectively. A sudden decrease in conductivity was observed for with ethylenediamine (EDA) modified GO (enGO), which is due to the blocking of epoxy groups. This experiment confirmed that the epoxide groups are the major contributor to the efficient proton transport. Because of a gradual improvement of the conduction path and an increase in the water content, σ values increase with the thickness of the multilayer films. The reported methods might be applicable to the optimization of the proton conductivity in other layered solid electrolytes.     

Preparation of Proton Conductive Inorganic-Organic Hybrid Films Using Epoxycyclohexylethyltrimethoxysilane and Orthophosphoric Acid

Proton conductive inorganic-organic hybrid films, which show high proton conductivity at temperatures higher than 100°C with low humidification, have been prepared from epoxycyclohexylethyltrimethoxysilane (EHTMS), 3-glycidoxypropyltrimethoxysilane, and orthophosphoric acid by the sol-gel method. Self-supporting, flexible, and brownish transparent films with a thickness ranging from 150 to 300 μm were obtained. Differential thermal analyses and thermogravimetric measurements revealed that the films were stable up to about 200°C. Ionic conductivity of the films increased with an increase in the content of phosphoric acid in the films. The films with a molar ratio of P/Si = 1.75 retained a high conductivity of about 6 × 10^?4 S cm^?1 even after holding for 150 h under 0.7% relative humidity at 130°C. The conductivity of the films increased with an increase in the relative humidity and was about 1 × 10^?2 S cm^?1 under 20% relative humidity at 130°C.