Self-healing of TiSiN/Ag coatings induced by Ag

Ceramic coatings often suffer from the formation and expansion of microcracks, which leads to a failure of the protective function. In this work, we observed self-healing of the microcracks in the TiSiN/Ag multilayer coating upon heating. This behavior can be attributed to diffusion of the Ag atoms to the cracks in the multilayer coating, while similar cracks in the TiSiN monolayer coating remain unchanged after the same treatment. Furthermore, the TiSiN/Ag coating with healed cracks possesses similar electrochemical corrosion and biofouling properties to the as-deposited one, suggesting that TiSiN/Ag is a promising system in marine engineering applications. The mechanism of self-healing was explained by kinetic simulations based on ab initio molecular dynamics and the diffusion activation energies of Ag in irregular ceramic structures have been calculated. The here adopted theoretical method also provides a new pathway for exploring new coating systems with a potential self-healing function.     

How Sulfur Controls Nucleation of Ag Islands on Ag(111)

Pre-adsorbed sulfur controls nucleation of Ag islands on Ag(111), at coverages above a very small critical value. Sulfur can exert opposite effects: it accelerates mass transfer of Ag to steps and hence inhibits nucleation under some conditions, but it impedes mass transfer and hence enhances nucleation under others. The effect depends upon sulfur coverage and temperature. The inhibition or acceleration of mass transfer correlates with the existence or absence of a semi-static, ordered arrangement of Ag₃S₃ clusters.     

Ag(I)/Ag electrode reaction in amide-type room-temperature ionic liquids

Ag(I)/Ag electrode reaction was investigated in some amide-type room-temperature ionic liquids composed of different cations. The morphology of silver deposits and the electrochemical behavior were not sensitive to the difference in the cations of ionic liquids. On the other hand, it was suggested that the adsorption of bis(trifluoromethylsulfonyl)amide (TFSA⁻) is more important for electrodeposition of silver in both ionic liquids and aqueous solutions. The diffusion coefficients of silver cation in the ionic liquids indicated the silver cation is surrounded by TFSA⁻ to form a bulky species. The rate of crystal growth of silver particles in the ionic liquids by electrochemical Ostwald ripening was much slower than that in a nitrate aqueous solution, suggesting the charge transfer in the ionic liquids is slower than that in the aqueous solution.     

Microstructure and optical properties of Ag/ITO/Ag multilayer films

Transflective and highly conductive Ag/ITO/Ag multilayer films were prepared by magnetron sputtering on glass substrates. The microstructure and optical properties of Ag/ITO/Ag multilayer films were systematically investigated by X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectroscopy. The optical properties of the multilayer films were significantly influenced by the thickness of the Ag surface layer from 3.0 to 12.6 nm. The multilayer film of Ag9.3nm/ITO142nm/Ag9.3nm shows the best comprehensive property. It could satisfy the requirement for transflective LCD.     

Equilibrium Phase Diagrams in the Systems PbO–Ag and CuO–Ag

Silver has played a critical role in the fabrication of metal/ high-T_c superconductor composites. Phase equilibrium in the binary PbO–Ag and CuO–Ag systems has been investigated using differential thermal analysis (DTA), thermogravimetry (TG), and X-ray diffractometry (XRD) techniques. Composition versus temperature diagrams have been established for these systems in air. Eutectic reactions CuO + Ag = L at a composition of Ag = 98.6 mol% and 932°± 3°C for the CuO–Ag system and PbO + Ag = L at a composition of Ag = 8.3 mol% and 825°± 3°C for the PbO–Ag system have been detected. The CuO–Ag system has two immiscible liquid phases in the composition regime of Ag = 30.6–98 mol%, and there are two immiscible liquid phases at the composition range of Ag = 11.7–95.7 mol% in the PbO–Ag system.     

电镀银和银合金

1　前言　　在装饰件或电子元件等基体上镀复银和银合金的镀液通常含有剧毒氰化物。于是人们致力于无氰镀液的研究 ,这些无氰镀液有 :(1)巯基烷基磺酸 巯基烷基羧酸镀液 ;(2 )烷基磺酸 烷基羧酸镀液 ;(3)氨基羧酸镀液 ;(4)以己内酰脲为络合剂的镀液 ;(5)以琥珀酸酰胺及其衍生物为络合剂的镀液 ;(6 )以硫代酰胺和硫醇化合物为络合剂的烷基烷磺酸 氨基磺酸镀液等 ,这些银和银合金无氰镀液存在的问题有 :(1)镀液稳定性较差 ,在较短的作业时间内便会生成黑色或者茶色沉淀 ,难以维持稳定的镀液组成 ;(2 )镀层平滑性和附着性问题 ;(3)镀液维护…     

Development of a Ag/Ag micro-reference electrode for electrochemical measurements in ionic liquids

We report on a novel miniaturized Ag/Ag⁺ reference electrode (RE) design suitable for electrochemical measurements in room temperature ionic liquids (RTILs). The electrode is based on capillaries with an outer diameter of 365 μm and contains a 10 mmol/l solution of a silver salt in a RTIL. The silver salt bears the same type of anion as the RTIL. While potential shifts of several hundred millivolts have been observed for common platinum or silver pseudo-reference electrodes, our Ag/Ag⁺ micro electrode provides a stable and reliable reference potential over a period of more than two weeks, if protected from light and stored in a nitrogen atmosphere. Due to the small dimensions of the RE, it can be placed close to the working electrode (WE) and it is well-suited for application in electrochemical micro cells as well as for potential-controlled in situ AFM, STM or electrochemical impedance measurements. The electrode characteristics were determined by voltammetric measurements on ferrocene and cobaltocenium hexafluorophosphate dissolved in a RTIL. The highest expected contamination of the sample with Ag⁺ ions was calculated and found to be below 4 ppm.     

Ag/Ag3PO4光催化降解乳酸左氧氟沙星

以AgNO3和Na2HPO4为原料,采用离子交换和超声辅助光致还原法制备具有可见光响应的高活性光催化剂Ag/Ag3PO4。采用X射线衍射、扫描电子显微镜、紫外–可见漫反射光谱等手段对其进行表征。以乳酸左氧氟沙星为模拟自然水体中残留的抗菌药物对光催化剂的性能进行了测定,考查了溶液初始pH值、乳酸左氧氟沙星初始浓度、催化剂用量、自由基清除剂对光催化效果的影响。结果表明:Ag/Ag3PO4光催化剂对乳酸左氧氟沙星表现出较强的光降解能力,当溶液pH=7、Ag/Ag3PO4用量为75mg、500W的可见光照射15min时,对初始浓度为30μmol/L乳酸左氧氟沙星降解率达到93.5%;循环使用4次后,光催化能力没有显著降低。电子空穴(h+)和超氧阴离子自由基(O2–)在光催化降解乳酸左氧氟沙星过程中起主要作用。     

Highly efficient and stable Ag/Ag3PO4 plasmonic photocatalyst in visible light

A highly efficient and stable photocatalyst Ag/Ag₃PO₄ was prepared by the ion-exchange process between AgNO₃ and Na₂HPO₄ and subsequently light-induced reduction route. The diffuse reflectance spectra (DRS) indicated Ag/Ag₃PO₄ had strong absorption in UV and visible-light regions. The composite showed excellent visible-light-driven photocatalytic performance. It can decompose organic dye within several minutes and still maintain a high level activity even though used five times. It is considered that this excellent performance results from the surface plasmon resonance of Ag nanoparticles and a large negative charge of PO₄^3 − ions.     

间位芳纶植入催化剂Ag预处理和无氨水镀浴化学镀银

采用植入催化剂Ag预处理法对间位芳纶(PMIA)进行表面改性,并在无氨水的镀银浴中进行化学镀银.其中,植入催化剂Ag预处理法主要包括3个步骤:丙酮超声除油,硝酸银/二甲亚砜水溶液溶胀渗透植入,以及硼氢化钠还原.无氨水镀浴体系则是以乙二胺和乙二胺四乙酸二钠作为复合络合剂实现对氨水的替代.制得的试样表面银镀层光滑、平整且致密,具有良好的力学性能、热稳定性及导电性,方块电阻为20～30 mΩ/sq,且在30～3000 MHz频率范围内的电磁屏蔽效能为68.23 dB.     

Resistance to sulfidation of the catalytic reduction of NOx over Ag/Al2O3 by controlling the loadings of Ag and Ag+

SO₂ strongly decreased the catalytic activities of low loading Ag/Al₂O₃ below 500 °C in selective catalytic reduction (SCR) of NO_x by propene with or without the assistance of non-thermal plasma (NTP), which was mainly attributed to the competition between SO₂ and NO. By controlling the loadings of Ag and Ag⁺ over alumina, the resistance of SO₂ was remarkably enhanced between 400 °C and 500 °C in thermal SCR. In the NTP-assisted SCR, most of the NO_x conversions were also apparently recovered from 250 °C to 500 °C.     

Reducing the solubility of Ag into BaTiO3 by alloying Ag with Pd

In the experiment reported in this study, a small amount of 70%Ag/30%Pd particles was mixed with BaTiO₃ powder and subsequently sintered at elevated temperature in nitrogen, air and oxygen. The solubility of Ag in the BaTiO₃ was determined using an electron probe microanalysis technique. The presence of Pd alloy in Ag can reduce its solubility and diffusion distance in BaTiO₃. Alloying with Ag significantly reduced the solubility of Pd in BaTiO₃.     

Nano-sized Ag–BaTiO3 composite powders with various amount of Ag prepared by spray pyrolysis

The preparation of precursors of BaTiO₃ nanopowders with various amounts of Ag by spray pyrolysis is reported. The precursor powders obtained with hollow and thin-wall particles are composed of uniformly dispersed Ba, Ti, and Ag components. After post-treatment and a simple milling process, the precursor powders, irrespective of the amount of Ag, are transformed into Ag–BaTiO₃ composite nanoparticles. The mean particle size of the Ag (10 mol%)–BaTiO₃ powders is 142 nm. BaTiO₃ pellets containing Ag exhibit dense structures even at a low sintering temperature of 1000 °C. BaTiO₃ pellets with 10 mol% Ag show the highest dielectric constant of 2950, as opposed to the pure BaTiO₃ pellets (without Ag), whose dielectric constant is 1827.     

Electrolytic studies on the system Ag/Ag2O/AgO in alkaline chloride solutions

Electrolytic silver oxide, formed by the constant current anodization of silver sinters in KOH electrolyte, has been found to be higher in AgO content when prepared in the presence of KCl than when prepared in pure electrolyte. The former AgO is considerably more stable in alkaline solution, seemingly due to the presence of residual AgCl. The formation of unstable oxy-chlorides at potentials more anodic than that for AgO formation results in the isolation of the AgO from the unoxidized Ag in the case of Ag foil electrodes, leading to suppression of the open circuit potential.     

Frequency response analysis of the Ag/Ag+ system: a partially active electrode approach

The dc and ac polarization behaviour of the Ag/Ag⁺ system was studied theoretically and experimentally. The model proposed is based on bulk diffusion towards a partially active electrode surface. The experimental data obtained on stationary and rotated disc electrodes of polycrystalline and monocrystalline silver in 0.1 M AgNo₃ + 1.0 M HClO₄ solution are interpreted in terms of different model parameters characterizing the dc and ac behaviour of the system quantitatively. It is demonstrated that surface relaxation may give rise to an inductive part in the ac-impedance diagram.     

Electrochemical window of molten LiCl-KCl-CaCl2 and the Ag/Ag reference electrode

The electrochemical window of an LiCl-KCl-CaCl₂ eutectic melt (52.3:11.6:36.1 mol%) was determined by cyclic voltammetry and open-circuit potentiometry at 723-873 K. The reaction at the anodic limit was confirmed to be Cl₂ gas evolution. The reaction at the cathodic limit was found to be a liquid Ca-Li alloy formation on the basis of ICP analysis of the deposits. An Ag⁺/Ag reference electrode separated with a Pyrex membrane showed good stability for more than 1 week. The standard electrode potential of Ag⁺/Ag was determined in the temperature range of 723-823 K by measuring the potential of a silver electrode in different concentrations of Ag⁺ ions.     

Size-Selected Ag Nanoparticles with Five-Fold Symmetry

Silver nanoparticles were synthesized using the inert gas aggregation technique. We found the optimal experimental conditions to synthesize nanoparticles at different sizes: 1.3 ± 0.2, 1.7 ± 0.3, 2.5 ± 0.4, 3.7 ± 0.4, 4.5 ± 0.9, and 5.5 ± 0.3 nm. We were able to investigate the dependence of the size of the nanoparticles on the synthesis parameters. Our data suggest that the aggregation of clusters (dimers, trimer, etc.) into the active zone of the nanocluster source is the predominant physical mechanism for the formation of the nanoparticles. Our experiments were carried out in conditions that kept the density of nanoparticles low, and the formation of larges nanoparticles by coalescence processes was avoided. In order to preserve the structural and morphological properties, the impact energy of the clusters landing into the substrate was controlled, such that the acceleration energy of the nanoparticles was around 0.1 eV/atom, assuring a soft landing deposition. High-resolution transmission electron microscopy images showed that the nanoparticles were icosahedral in shape, preferentially oriented with a five-fold axis perpendicular to the substrate surface. Our results show that the synthesis by inert gas aggregation technique is a very promising alternative to produce metal nanoparticles when the control of both size and shape are critical for the development of practical applications.     

Ag exchange at Cds electrode surfaces

The inhibition effect of Ag⁺ ions on the photoanodic corrosion of CdS semiconductor electrodes has been studied in 0.5 M NaClO₄ + xM AgClO₄ solutions (0 x 10⁻², pH = 2) by means of potentiostatic current density-potential measurements, ac-impedance and atomic absorption. In the presence of Ag⁺ ions in the solution a thin Ag₂S film of ca. 30–300 nm thickness is formed on the CdS surface due to the heterogeneous cation exchange reaction CdS + 2Ag⁺ = Ag₂S + Cd²⁺. The Ag₂S film formation is a transport controlled process which can be described by a parabolic rate law. From kinetic investigations in the temperature range (298 T 348 K) the activation energy of this process was determined to be about 62 kJ mol⁻¹. Information about the morphology and composition of the surfaces was obtained from optical and scanning electron microscope investigations including EDAX.     

纳米银修饰电极的制备

在圆柱形电解槽中,采用直流电沉积方法在导电玻璃上沉积银纳米材料,制备了Ag／ITO、Ag／CNTs／ITO复合电极,并以制得的复合电极作工作电极,测定两种电极在磷酸缓冲溶液中的循环伏安响应曲线。实验结果表明,纳米银修饰的电极具有很好的电化学活性。