Morphology Of Silver Nanowires Research Articles

Synthesis and morphology of Ag nanowires by fiber template method

The synthesis of traditional silver nanowires often uses a polyol method. There are many factors that affect the structure of silver nanowires, such as silver ion concentration, type and amount of reducing agent, oxygen concentration, stirring speed, temperature, and time. The synthesis conditions are harsh and difficult to replicate. In this paper, natural fibers and synthetic fibers were used as templates to assist the polyol reduction method to obtain silver nanowires with uniform structure. The effect of fiber types on the structure of silver nanowires were studied, including hemp fibers, wheat straw fibers, tobacco stem fibers, and polycarbonate fibers. Polycarbonate fibers induced the synthesis of silver nanowires with the highest aspect ratio, highest yield, and most uniform diameter distribution. The effect of polycarbonate fibers concentrations on the morphology and conductivity of silver nanowires were also studied. When the polycarbonate mass concentration was 8.5 × 10−4 g/mL, the aspect ratio of silver nanowires was the highest. The effect of polycarbonate fibers length (2 mm\\5 mm\\7 mm) on the morphology of silver nanowires were also studied. When the length of the template polycarbonate fibers was 7 mm, the length to diameter ratio and conductivity of the nanowires obtained are the best. Furthermore, the reaction kinetics of the reaction were studied via multiple sampling of silver nanowire reaction solutions and characterized by using UV–visible spectroscopy and scanning electron microscopy. The synthesis method of silver nanowires using fiber template is simple and fast, and can be used to synthesize silver nanowires with uniform diameter distribution on a large scale, thus solving the bottleneck problem of harsh synthesis conditions for silver nanowires. The resulting silver nanowires were blended with carboxymethyl cellulose to prepare conductive inks, which were coated on paper and cured at 180 °C for 30 min to achieve good conductivity.

Mechanism of Heat-Induced Fusion of Silver Nanowires

Physical changes in arranged silver nanowires were monitored during progressive heating inside a transmission electron microscope. Using the in-situ experimental method, overall variation of silver nanowires and movement of the silver atoms could be assessed. The physical morphology of silver nanowires was rapidly transformed above 350 °C as they fused with each other, which led to extrusion of the silver atoms. Around 550 °C, silver nanowires were almost fused into one, filling a relatively large void between silver nanowires. However, above 575 °C, the united silver nanowire was completely cut off, starting from the region that was suspected to have defects. For the first time, the fusion of arranged silver nanowires and the configurational changes of silver atoms during heating were visualized, and the migration between silver atoms and the damage mechanism of silver nanowires were assessed. Moreover, the relationship of physical morphology and electrical property of silver nanowires according to the temperature were investigated using the ex-situ experimental method. As silver nanowires started to split at 300 °C, the electrical conductivity deteriorated greatly. Beyond 350 °C, the electrical conductivity was completely lost while silver nanowires disintegrated rapidly, and silver nanowires completely disappeared at 450 °C.

EFFECTS OF SYNTHESIS CONDITIONS ON THE FORMATION AND MORPHOLOGY OF SILVER NANOWIRES

Silver nanowires with one-dimensional structures have attracted much research interest due to their potential applications in several areas. It is well-known that their properties strongly depend on the size and morphology of the silver nanostructures. Therefore, in our work, silver nanostructures were prepared using a polyol process and the effects of synthesis conditions on the formation and morphology of silver nanowires were investigated. The structure and morphology of the synthesized silver nanostructures were characterized using transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The results showed that the morphology of the silver nanowires can be effectively controlled via adjusting parameters of the synthesis process.

Synthesis and Characterizing of High Aspect Ratio Silver Nanowires by Polyol Process

Silver nanowires with controllable and high length-diameter ratio were prepared by using the reductibility of ethylene glycol under high temperature and selective adsorption of PVP. AgNO3, ethylene glycol, PVP and CuCl2was used as the silver source, the reductant, the capping agent and the ion additives, respectively. The effects of centrifugal rate, silver ions' concentration, AgNO3adding rate on the morphology of silver nanowires were investigated by SEM, XRD, TEM and other technologies. The results show that the optimal centrifugal rate is 2000n/s, the better silver ions’ concentration is 6.55 mg/mL, and the best rate of adding AgNO3is 6 ml/min. The silver nanowires with an average diameter of 74.9 nm, the average length of 45.5μm and its length-diameter ratio of 607.5 are obtained. The silver nanowires with good morphology and high length-diameter ratio are adjustable, which is suitable for the preparation of OLED transparent film electrode materials, and other conductive materials.

Synthesis of Silver Nanowire and Preparation of Uniform, Highly Conductive Transparent Films on Flexible Substrate with Extremely Excellent Film Performance

Silver nanowires were successfully synthesized by the two-step injection polyol method. Reaction time and centrifugation speed are critical factors enabling high length and diameter ratio of silver nanowires. The effects of the two factors on the morphology of silver nanowires were investigated in the experiment of synthesis of silver nanowires, respectively. The optimal experimental conditions are that the reaction time is 1 hour and the centrifugal speed is 2000 rpm. The length and diameter of the prepared silver nanowires reaches 5–10 μm and 60 nm, respectively. Silver nanowires were used for preparing transparent conductive film through vacuum filtration method, and then transferred to polyethylene glycol terephthalate (PET) substrate. The adhesive ability between the substrate and silver nanowire layer is greatly improved with spinning Polyvinylidene Fluoride (PVDF) on the silver nanowire network. Silver nanowire network on PET substrates showed an excellent stability, a good combination of high electrical conductivity and light transmittance. The transmittance of silver nanowires film reaches 71.5% and resistance is 65.5 ohm/sq. And the sheet resistance decreased significantly while the light transmittance had a little change when spun coated PVDF solutions on top of the silver nanowire film.

Research on the Controllable Preparation of Silver Nanowires in Conductive Adhesives

One dimensional nanomaterials are used as the basic and significant parts to fabricate nanodevices. Silver nanowire is a promising conductive particle, which can be used in conductive adhensives. The research is about the effects of the control agents, reaction temperature, and reaction time on the morphology and size of the product. And figure out an effective way to control the nucleation and the morphology of silver nanowires.

Tailoring of Structural Morphology of Silver Nanowires in Electrochemical Growth

ABSTRACTNoble metal such as Ag normally exists in an fcc crystal structure. However as the size of the material is decreased to nanometer lengthscales, a structural transformation from that of its bulk state can be expected with new atomic arrangements due to competition between internal packing and minimization of surface energy. In many previous studies, it has been shown that silver nanowires (AGNWs) grown inside anodic alumina (AAO) templates by ac or dc electrochemical deposition from silver salts or complexes, adopt fcc structure and below some critical diameter ∼ 20 nm they may acquire hcp structure at low temperature. This is, however, critically dependant on the nature of confinement, as AgNWs grown inside nanotube confinement with subnanometer diameter have been reported to have fcc structure. Hence the question of the crystal structure of metal nanowires under combined influence of confinement, temperature and deposition condition remains open. In this abstract we show that the alternative crystal structures of AGNWs at room temperature can be achieved with electrochemical growth processes under specific conditions determined by the deposition parameters and nature of confinement. We fabricated AgNWs of 4H hexagonal structure with diameters 30 – 80 nm inside polycarbonate (PC) templates with a modified dc electrodeposition technique, where the nanowires were grown at deposition potentials as low as 10 mV in 2 M silver nitrate solution[1]. We call this low-potential electrodeposition (LPED) since the electrodeposition process occurs at potential much less than the standard Nernst potential (770 mV) of silver. Two types of electrodes were used – stainless steel and sputtered thin Pt film, neither of which had any influence on the crystal structure of the nanowires. EDS elemental analysis showed the nanowires to consist only of silver. Although the precise atomic dynamics during the LPED process is unclear at present, we investigated this with HRTEM (high-resolution transmission electron microscopy) characterization of nanowires grown over various deposition times, as well as electrical conductivity measurements. These experiments indicate that nanowire growth does not occur through a three-dimensional diffusion controlled process, as proposed for conventional over-potential deposition, but follow a novel instantaneous linear growth mechanism. Further experiments showed that, (a) conventional electrochemical growth at a small over-potential in a 2 mM AgNO3 solution yields nanowires with expected fcc structure inside the same PC templates, and (2) no nanowire was observed under the LPED conditions inside hard AAO templates, indicating that LPED-growth process, and hcp structure of the corresponding nanowires depend on deposition parameters, as well as nature of confinement.