单分散性银纳米粒子的可控制备

以卤化银或氧化银作为前驱体,室温下以水为溶剂,在较高溶液浓度下,利用化学还原法制备了单分散性银纳米粒子,并通过改变前驱体的种类,实现了粒径可控制备。采取扫描电子显微镜（SEM）、紫外-可见光谱仪（UV-Vis）、X射线-粉末衍射仪（XRD）、X射线-光电子能谱仪（XPS）等对所制备的银纳米粒子的形貌及成分进行了表征。结果显示,所制备的银纳米粒子具有较高的单分散性,粒径在40~150 nm之间,具有面心立方多晶结构。该方法制备的银纳米粒子可用于喷墨打印RFID天线。     

Phytochemical fabrication and characterization of silver nanoparticles by using Pepper leaf broth

The Pepper leaves extract acts as a reducing and capping agent in the formation of silver nanoparticles. A UV–Vis spectrum of the aqueous medium containing silver nanoparticles demonstrated a peak at 458 nm corresponding to the plasmon absorbance of rapidly synthesized silver nanoparticles that was characterized by UV–Vis spectrophotometer. The morphology and size of the benign silver nanoparticles were carried out by the transmission electron microscope (TEM) and field emission scanning electron microscope (FE-SEM). The sizes of the synthesized silver nanoparticles were found to be in the range of 5–60 nm. The structural characteristics of biomolecules hosted silver nanoparticles were studied by X-ray diffraction. The chemical composition of elements present in the solution was determined by energy dispersive spectrum. The FTIR analysis of the nanoparticles indicated the presence of proteins, which may be acting as capping agents around the nanoparticles. This study reports that synthesis is useful to avoid toxic chemicals with adverse effects in medical applications rather than physical and chemical methods.     

Fabrication of flexible conducting thin films of copper-MWCNT from multi-component aqueous suspension by electrodeposition

Flexible thin films of metal–carbon nanotube (CNT) with densely populated CNT morphology were fabricated by electrodeposition from an optimized copper bath. The substrate used for the present work is polyethylene film that was pre-deposited with electroless copper as a seed layer before CNT deposition. Optimum concentration of CNT was incorporated into copper bath and the electrodeposition was done at quiescent and agitation conditions. The bonding between the seed layer and the electrodeposited copper was good as revealed from adhesion test. Electrical as well as physical-mechanical property of the film was improved by CNT incorporation within the metal matrix. The topography and the texture of the metal–CNT deposit showed a well-refined structure as per scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM), and scanning probe microscope (SPM) analysis. The stability of the film was tested by cyclic voltammetric and stripping analysis under various applied conditions. Raman spectra and Fourier transfer infrared spectroscopic (FT-IR) analysis revealed the presence of CNT and the functionality of CNT within the copper matrix. Transmission electron microscope (TEM) analysis showed nucleation of copper on the surface of CNT walls.     

Synthesis of colloidal silver nanoparticles for printed electronics

Colloidal silver particles were successfully prepared by wet chemical synthesis. The pure single phase of silver was confirmed by X-ray diffraction. Transmission electron microscope categorized that the diameters of particles were 100 and 20 nm, depending on the molecular weight of the PVP stabilizer. A schematic drawing model was used to predict the packing efficiency of 1:1 wt% of two mixtures. The mixture of silver solution was deposited as a thin solid film by a desktop inkjet printer. Scanning electron microscope showed that two different sizes of silver particles give higher densely packed structure than the film of single particle size. When a 0–20 V voltage was applied, the current density reached was 0.10 J/cm², suggesting that the silver film has potential to be applied as a cathode layer in organic light emitting diode (OLED) devices.     

Monodisperse copper‐ and silver‐nanocolloids suitable for heat‐conductive fluids

Copper colloid was prepared via reductive stabilization. The suspension of the trioctylaluminum‐stabilized copper colloid was peptized using Korantin SH and cashew nut shell liquid (CNSL). Fluids with particle sizes <10 nm were obtained with Korantin and 7–15 nm in the case of CNSL. However, the copper colloid is air sensitive. A very straightforward one‐step method leads to air‐stable silver nanofluids. Thermal decomposition of silver lactate in the presence of Korantin SH and mineral oil as the medium gave a silver nanofluid. Silver particle formation and air stability were monitored using UV–VIS spectroscopy. The presence of monodispersed spherical silver nanoparticles was confirmed. Transmission electron microscopy showed a two‐dimensional assembly of the silver particles with a size distribution of 9.5 ± 0.7 nm. FTIR has revealed information about the interaction between the surfactant and the silver surface. Copyright © 2005 John Wiley & Sons, Ltd.     

醇热法合成单晶银纳米线及其表征

以硝酸银为前驱物, 聚乙烯醇缩丁醛(PVB)为结构导向剂, 通过醇热法, 反应温度为140 ℃, 反应时间为24 h的条件下制备了银纳米线. 采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、热重分析(TG)、红外光谱(FT-IR)和激光拉曼光谱(Raman)等手段对产物进行了系统表征, 结果表明: 所得银纳米线具有面心立方结构, 沿着(111)晶面生长, 具有单晶结构; 考察了反应温度和时间对产物形貌的影响, 结果表明: 反应温度和时间在形成银纳米线的过程中起着关键的作用; 银纳米线具有较强的表面增强拉曼散射效应; 同时提出了银纳米线可能的晶化机理.     

银纳米颗粒的合成及其与曙红Y的相互作用

分别制备了以L-半胱氨酸(L-cyst.)或以巯基乙酸(TGA)保护的银纳米颗粒,并用紫外-可见分光光度法和透射电子显微技术(TEM)对两种不同状态的银纳米颗粒的结构作了表征。由其吸收光谱图显示,L-cyst.和TGA保护的银纳米颗粒的吸收峰依次位于384 nm和392 nm波长处;由TEM的检测结果表明:上述2种形态银纳米颗粒的粒度大小依次在10~40 nm和20~30 nm范围内。试验中发现,以L-cyst.保护的银纳米颗粒与曙红Y之间有明显的相互作用,导致其吸收峰从384 nm红移至395 nm;以TGA保护的银纳米颗粒与曙红Y之间未见有相互反应。初步探讨了其作用机理,认为系由于结合于银纳米颗粒表面的L-半胱氨酸分子所带的正电荷与曙红Y分子上的负电荷之间的静电作用的结果。     

Energy Dispersive X-Ray Fluorescence Analysis and X-Ray Microanalysis of Medieval Silver Coins

 Austrian medieval silver/copper coins were investigated at their surfaces by energy dispersive X-ray fluorescence analysis (EDXRF) and at the cross-sections by X-ray microanalysis in the scanning electron microscope (SEM/EDX) in order to estimate the error occurring when corroded objects of art and archaeology are analyzed on the surface by non-destructive methods. Additionally, Ag/Cu-standards were treated in diluted sulphuric acid and the depletion of copper on the surface was measured by EDXRF. By calculating the ratio of the Ag-K/Ag-L intensity the process of blanching could be studied.     

新型中空卤化银颗粒乳剂的制备和性能研究 Ⅳ.利用非水溶剂制备中空卤化银颗粒乳剂

有近160年历史的银盐卤化银乳剂制备的感光材料,到目前为止仍不失为一种优良的信息记录材料。但昂贵的白银的缺乏和消耗,使得节银和降低成本成为银盐感光材料生产中急需要解决的问题。     

Fabrication and Photocatalytic Properties of Water-stable Ag/PW12/PVA Nanocomposites

A kind of water-stable phosphotungstic acid/polyvinyl alcohol(PW₁₂/PVA) fiber was prepared by thermal or chemical crosslinking treatments with the help of electrospinning, and silver nanoparticles(NPs) modified fibrous precursor was successfully obtained by photoreduced method. The nanocomposites were characterized by transformation infrared spectroscopy(FTIR), UV-Vis diffuse reflection spectroscopy(DRS), field environmental scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that the sizes of silver NPs are about 20 or 40 nm on thermally or glutaraldehyde(GA) vapor crosslinked PW₁₂/PVA fiber, respectively. As a photocatalyst, PW₁₂/PVA fiber possesses high surface area to volume ratio, stable recyclability, and efficient transportation of electrons under visible light. The nanohybrids exhibit excellent photocatalytic activity for the degradation of Rhodamin B than PW₁₂/PVA nanofiber.     

All‐organic nanocomposites of functionalized polyurethane with enhanced dielectric and electroactive strain behavior

For a dielectric elastomer, increasing its dielectric constant substantially could lead to a high electric field induced strain under a low operation field. In this work, high dielectric constant nanocomposites were developed by chemically bonding copper phthalocyanine oligomer (CuPc), a high dielectric constant organic semiconductor, to polyurethane (PU). Transmission electron microscope‐observed morphologies revealed that the sizes of CuPc particles in a nanocomposite of PU attached with 8.78 vol.% of CuPc were in the range of 10–20 nm, much smaller than the sizes (250–600 nm) in physical blend of PU with the same volume fraction of CuPc. At 100 Hz, the nanocomposite film exhibited a dielectric constant of 391, representing a more than 60 times increase with respect to the neat PU. The enhanced dielectric response in the nanocomposite makes it possible to induce a high electromechanical response. A strain of 17.7% and an elastic energy density of 0.927 J/cm³ were achieved under an electric field of 10 V/µm. Copyright © 2014 John Wiley & Sons, Ltd.     

稀土镧对真空蒸发沉积银纳米粒子团聚的影响

用透射电镜（TEM）和扫描电镜（SEM）研究了稀土镧对真空蒸发沉积银纳米粒子的影响.结果表明,稀土镧对真空蒸发沉积银纳米粒子有明显的细化作用.稀土镧对银纳米粒子的细化作用,是由于稀土镧增强了基底对银原子的吸附能,使镧和银结合形成的复合小银粒子局限于固定位置,进而减少了相互团聚所致.     

One‐step Hydrothermal Synthesis and Assembly of Copper and Silver Nanoparticles to Aggregates in Glyoxal Reduction System

A simple hydrothermal process has been developed for the synthesis and assembly of copper and silver nanoparticles to aggregates. The reduction of Cu²⁺ and Ag⁺ ions to the zerovalent metal was performed by glyoxal in the absence of any external agent. The produced glyoxylic acid (GA) in the redox process stabi‐ lized metallic copper and silver particles and rendered them oxidation resistant for several months and dispersible in polar organic solvents and water. Detailed nanostructures of synthesized products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD). The results demonstrated that assembly of nanoparticles to aggregates and their regularity were dependent on the reaction conditions such as temperature and concentration of the starting material. The Ostwald ripening process was proposed to explain the formation of copper nanoparticles by TEM observation at several times during the reaction. The existence of the surface stabilizing agent was identified by Fourier Transform infrared spectroscopy (FT‐IR) and thermogravimetric analyses (TGA).     

A simple approach to the synthesis of silver nanowires by hydrothermal process in the presence of gemini surfactant

Silver nanowires were synthesized by the hydrothermal route in aqueous solution of gemini surfactant 1,3-bis(cetyldimethylammonium) propane dibromide (16-3-16) at a relatively low temperature. The as-prepared silver nanowires were characterized by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), transmission electron microscope (TEM), electron diffraction (ED), and UV-vis absorption spectrum. The obtained silver nanowires are of high aspect ratios with an average diameter of approximately 30 nm and length ranging from several to tens of micrometers.     

电子显微镜技术表征聚乙二醇包覆的银纳米线的显微结构特征

以缓慢的水热合成法制备聚乙二醇(PEG)包覆的银纳米线,并用电子显微镜对其微观形貌和结构进行了表征。PEG是一种对银表面呈弱亲和性的水溶性聚合物,它在银纳米线合成中既作为Ag+的还原剂,又作为银线的包覆剂。扫描电镜和透射电镜表征显示,这种银纳米线的直径为80～300 nm,长度大于100μm;并且其中一部分银纳米线首尾相接形成了闭合纳米线圈,是首例以化学法制取的金属闭合纳米线圈。闭合环状纳米线的形成进一步支持了金属纳米线的融合生长机制。透射电镜和选区电子衍射以及银纳米线横截面切片的透射电镜表征显示,这种PEG包覆的银纳米线具有轴对称的五重挛晶结构。银纳米线经过长时间的水热孵化而保持其五重挛晶结构,这一点与某些文献报道的情况有所不同,说明银纳米线结构及其演化具有一定的复杂性。     

Examination and analysis of Indian silver punch‐marked coins employing WD‐XRF and other noninvasive techniques

The archaeometallurgical analysis of ancient silver coins provides useful information regarding fabrication methodology, provenance, and trade route and explains large diversification in elementary composition, weight, and physical features. The present investigation deals with the chemical analysis and examination of the processing history of Indian punch‐marked silver coins dating to 400–200 bc . The chemical analysis was carried out by wavelength dispersive X‐ray fluorescence and X‐ray Diffraction (XRD). The microstructural examination was performed using field emission scanning electron microscope (FE‐SEM) and different phases were identified by Scanning Electron Microscopy coupled with Energy Dispersive X‐ray (SEM‐EDX) Spectroscopy. It was observed that all eight coins were manufactured with silver‐copper alloy. The ore used for obtaining silver was argentiferous galena, and cupellation was carried with perfection. The absence of slag inclusions as revealed by SEM examination indicated that coins (numbers 2, 4, 5, and 7) were cast from a molten state. The presence of Cu₂O, CuO, and Ag₂O on the surfaces of the coins was confirmed by XRD. The formed oxide layers provided protection and saved the coins from bulky corrosion products. The data reveal great divergence of coin surface from the composition of the core with the far better metallurgical process for refining of silver for this hoard.     

聚合物存在下纳米银复合材料的制备与表征

以聚丙烯腈聚乙二醇嵌段共聚物PAN-b-PEG-b-PAN为稳定剂, 在超声辐照下成功地制备了分散性较好、尺寸均匀的纳米银颗粒. 用X射线衍射(XRD)、红外光谱(FTIR)、透射电镜(TEM)、紫外-可见吸收光谱(UV-Vis)和热分析(TGA)等对制备的纳米银复合材料进行了表征. 红外结果表明超声辐照并没有破坏聚合物的链结构. 聚合物的引入, 对纳米银颗粒起到了很好的分散保护作用. 用低浓度的硝酸银溶液, 得到粒径较小的纳米银颗粒; 随着硝酸银浓度增大, 纳米银颗粒粒径也增大. 而聚合物的浓度增大时, 所得银纳米颗粒粒径减小. 对银纳米颗粒的形成机理进行了讨论.     

Electric field effect on the vibration of single CO molecules in a scanning tunneling microscope junction

A low-temperature scanning tunneling microscope (STM) and ab initio calculations were used to study the electric field effect on the vibration of single CO molecules in an STM junction at 13 K. The vibrational energy of CO molecules adsorbed on silver atoms, measured by STM-based inelastic electron tunneling spectroscopy, depends on the direction of the electric field applied between the STM tip and the silver species. This characteristic can be explained by the charge separation model. The electric field modifies the binding characteristics of CO on silver as a result of a change in the charged states of the species, which leads to an increase (or a decrease) of the energies of the hindered rotation and the CO stretch on silver.     

An infrared study on the chemisorption of tertiary phosphines on coinage and platinum group metal surfaces

The chemisorption of dimethylphenyl-, methyldiphenyl- and triphenylphosphine on evaporated gold, silver, copper, rhodium, iridium, palladium, platinum and nickel surfaces has been studied by means of infrared reflection–absorption spectroscopy (IRAS). Multilayers of physisorbed phosphine are formed on the surfaces of all metals studied except nickel after deposition from dilute toluene solution. The deposition rate varies for different metal surfaces and it is sometimes quite slow. The standard immersion time was 20 h in this study to secure that an equilibrium between the surface and the solution is reached. Several minutes of ultrasonic treatment are required to get rid of the physisorbed phosphine, leaving a very thin layer of chemisorbed phosphine on the metal surface. Most of the absorption bands in IRAS spectra of these thin layers show significant shifts, which are especially large for dimethylphenylphosphine. It is evident that the electron distribution in the entire phosphine molecules is changed and that the chemisorption to the coinage and platinum group metal surfaces is strong. Infrared spectra of coordination compounds of gold(I), silver(I) and copper(I) with dimethylphenyl-, methyldiphenyl- and triphenylphosphine and of the corresponding phosphine oxides have served as reference material for the chemisorbed phosphines. The spectra of the coordination compounds show similar shifts and intensity changes as the IRAS spectra of tertiary phosphines chemisorbed on the coinage and platinum group metals. This suggests that the studied phosphines are as strongly bound to the coinage and platinum group metal surfaces as to the monovalent coinage metal ions known to form very stable complexes with tertiary phosphines.     

New complex transition metal carbides formed on an electron microscope heating stage

Particles shown to be complex carbides of copper. nickel, molybdenum.tungsten. gold, silver and titanium along with carbides of the elements in stainless steel, were formed on an electron microscope heating stage. These particles were observed to form on thin carbon films coating the electron microscope grids of the metals listed above. The d-spacings measured for these particles are essentially the same as those that are observed with a mixture of the complex carbides of general formula M₆C and M₂₃C₆. Electron microprobe analysis was performed on the particles formed in the microscope. and the analysis confirmed the presence of the respective metals within the particles. In general, the various metal carbides were observed to form at different temperatures on different metal grids.