Nanostructured Silver Thin Films Research Articles

Nanostructured Silver Thin Film: Using Successive Ionic Layer Adsorption and Reduction Method

The Successive Ionic Layer Adsorption and Reduction (SILAR) method was utilized to produce nanostructured silver thin films on a glass substrate. Ag nanoparticles were grown using SILAR parameters such as silver nitrate (AgNO3), reduction time, reduction agent in an aqueous solution of hydrazine hydrate with various concentrations, and growth cycles. In this study, X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-visible-NIR absorption spectroscopy techniques were used to assess the produced silver thin film nanostructure. The size and spreading of the formed silver nanoparticles are observed to grow with the reducing agent and eventually saturate for constant growth cycles. As a result, the size and the distribution of the produced Ag nanoparticles grow uniformly. Higher growth cycles, however, caused Ag nanoparticles to lose their homogeneity and change into gravel-shaped particles. Therefore, silver nanoparticles that have been produced with the ideal SILAR conditions can be employed as an extremely sensitive, repeatable substrate with an exceptionally efficient factor. Moreover, the Effect of the concentration of HyH on the properties of SILAR-grown silver thin films has been extensively studied.

Impact of Surface Functionalization by Nanostructured Silver Thin Films on Thermoplastic Central Venous Catheters: Mechanical, Microscopical and Thermal Analyses

In this work, an interdisciplinary approach was employed to investigate the impact on thermoplastic catheters from the deposition of a thin (180 nm), metallic silver film by a pulsed ablation technique. Our characterization firstly involved tensile and bending tests, each one accompanied by finite element modeling aiming to elucidate the contributions resulting from bulk and coating to the device’s mechanical behavior. The morphological assessment of the surface before and after the deposition was performed by atomic force microscopy, specifically implemented to visualize the nanostructured character of the film surface and the extent to which the polymer was modified by the deposition process, focusing on coating delamination due to tensile stress. Finally, thermogravimetric–differential thermal analysis was carried out to evaluate whether silver deposition has affected the physiochemical structure of the polymer matrix. Our results establish that the deposition does not significantly alter the physical and chemical properties of the device. The presented characterization sets a useful precedent for elucidating how structural properties of polymeric materials may change after coating by electronic ablation techniques, highlighting the importance of employing a comprehensive approach for clarifying the effects of additive manufacturing on medical devices.

On the influence of the mass ablated by a laser pulse on thin film morphology and optical properties

To know and to control experimental parameters that play a role in laser ablation is vital to define film properties. Among the others, laser fluence is commonly used. Yet, when plasma expansion dynamics takes place through an ambient gas, the relation between the ablated mass per pulse and gas mass is critical and till now it was poorly investigated. While the gas mass is fixed by the pressure in the deposition chamber, the ablated mass is not unequivocally determined by the laser fluence. For a given fluence value the ablated mass changes as a function of the irradiated target area. Here, we show that nanostructured silver thin films deposited keeping unaltered the laser fluence, while changing in a controlled way the irradiated area and hence the ablated mass per pulse, display markedly differentiated morphological and optical properties, as evidenced by electron microscopy and UV–Vis and Raman spectroscopies.

Mechanistic Study of Silver Nanoparticle Formation on Conducting Polymer Surfaces

Conducting polymer (polyaniline) sheets are shown to be active substrates to promote the growth of nanostructured silver thin films with highly tunable morphologies. Using the spontaneous electroless deposition of silver, we show that a range of nanostructured metallic features can be controllably and reproducibly formed over large surface areas. The structural morphology of the resulting metal-polymer nanocomposite is demonstrated to be sensitive to experimental parameters such as ion concentration, temperature, and polymer processing and can range from densely packed oblate nanosheets to bulk crystalline metals. The deposition mechanisms are explained using a diffusion-limited aggregation (DLA) model to describe the semi-fractal-like growth of the metal nanostructures. We find these composite films to exhibit strong surface-enhanced Raman (SERS) activity, and the nanostructured features are optimized with respect to SERS activity using a self-assembled monolayer of mercapto-benzoic acid as a model Raman reporter. SERS enhancements are estimated to be on the order of 10(7). Through micro-Raman SERS mapping, these materials are shown to exhibit uniform SERS responses over macroscopic areas. These metal-polymer nanocomposites benefit from the underlying polymer's processability to yield SERS-active materials of almost limitless shape and size and show significant promise for future SERS-based sensing and detection schemes.

Surface characterization of aromatic thermotropic liquid crystalline fiber deposited by nanostructured silver

Nanostructured silver thin films were sputtered onto the aromatic thermotropic liquid crystalline fibers of Vectran by magnetron sputtering technology. Plasma treatment was used as pre-treatment in order to improve the deposition of the coating layer. Surface morphology of the coated fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A full energy dispersive X-ray analysis (EDX) was used to detect the elemental composition of the material. Its conductivity and mechanical properties were measured and analyzed as well. The study revealed that a very thin conductive silver deposition exhibited high electrical conductivity as well as less influence on the mechanical properties of the pre-treated Vectran fiber. The plasma treatment could improved the deposition of the coating layer, but the surface roughness caused by plasma treatment also affected the surface conductivity. It was found that the surface resistivity could reach very low value of 1.66×10−3 Ω·cm after sputtering deposition for 30 min.

Laser-induced micron and submicron ordering effects in quasi-percolated nanostructuredsilver thin films

Quasi-percolated nanostructured silver thin films are used as the starting morphology forinducing simultaneously changes in shape and ordering effects by laser irradiation. Thecomplex fingered nanostructures are transformed into nanospheres which in turn arearranged in micro-circular patterns when irradiated through a pinhole. Thesetransformations are characterized by transmission electron microscopy and atomic forcemicroscopy. The observed effects are explained using Fresnel diffraction theory. Goodagreement with the experimental results is obtained. These results suggest thatprecise patterning engineering can be achieved through control of the spatialparameters such as the pinhole diameter and the distance from the mask to the sample.

The controlled pulsed laser deposition of Ag nanoparticle arrays for surface enhancedRaman scattering

An effective method for the production of surface enhanced Raman scattering (SERS)active substrates is presented. Nanostructured silver thin films are pulsed laser deposited inan argon atmosphere. The films consist of arrays of nanoparticles whose size is controlledby the Ar pressure. The surface morphology of the films can be tuned by the laser pulsenumber. Nanoparticle size is calculated by a phenomenological model taking intoaccount the dynamics of the laser generated silver plasma. The SERS activity of thefilms is investigated by Raman scattering of adsorbed rhodamine 6G at differentconcentrations.

Superhydrophobic Coatings with Reduced Ice Adhesion

A brief description of how superhydrophobicity can help mitigate the ice accretion problem on power network equipment and other exposed structures by reducing ice-to-surface adhesion is presented. Basic models, namely the Wenzel and Cassie–Baxter models, accounting for the contact angle of water on solid surfaces relating to the influence of surface roughness on hydrophobicity are discussed. The results on superhydrophobic aluminum surfaces, superhydrophobic nanostructured silver thin films, superhydrophobic nanostructured zinc oxide as well as superhydrophobic nanofibres are also discussed. Some of the superhydrophobic surfaces were tested for ice adhesion and a reduced ice adhesion was obtained.

Step-wise Ag thin film patterns fabricated by holographic lithography

A laser-induced thermo-elastic removal was used to pattern nanostructured silver thin films solution-deposited on the glass substrate. We show that sharp-edged patterns can be fabricated under an interference-generated gradual intensity profile. The etching behavior and the resulting pattern morphology were very sensitive to the cohesion of the film and its adhesion to the substrate, being both modified by the post-deposition annealing process. The fabrication of step-wise one-dimensional (1D) and 2D patterns at the micrometer scales is demonstrated by holographic lithography using an Nd:YAG pulsed laser, along with a discussion on the effect of film cohesion and adhesion.

Nanostructured silver thin films deposited by pulsed laser ablation

Nanostructured thin films were deposited by excimer laser ablation of silver targets in controlled atmospheres of He and Ar. The film structural properties were investigated by means of scanning electron microscope and transmission electron microscope imaging. The film growth mechanism was identified as the result of coalescence of nanometric clusters formed during plume flight. Cluster formation involves plume confinement as a consequence of the increased collisional rate among plasma species. Fast photography imaging of the laser-generated silver plasma allowed to identify plasma confinement, shock wave formation and plasma stopping.

Atomic force microscopy and X-ray photoelectron spectroscopy study on nanostructured silver thin films irradiated by atomic oxygen

Nanostructured silver thin films irradiated by atomic oxygen (AO) generated in a ground simulation apparatus were investigated by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM results show that after irradiation, all the grain sizes of the thin films became more or less small, and the compact surface became rough and sparse. From XPS depth profile of an AO-irradiated silver thin film, it can be found that the silver oxides formed exist as two valences, that is, at the surface, the oxide is mainly AgO, and gradually change to Ag 2O, the content of unoxidized silver also increase with depth of film.

Preparation and characterization of nanostructured silver thin films deposited by radio frequency magnetron sputtering

Nanostructured silver thin films were prepared by radio frequency magnetron sputtering at room and liquid nitrogen substrate temperatures. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to study the topography and chemical composition, respectively, of the thin films. The AFM results indicate a significant difference in the morphology of the thin films when argon or nitrogen ions were used as sputtering ions. For argon ion sputtering, a difference also exists in the microstructure and topography of the thin films for ambient and liquid nitrogen substrate temperatures. The XPS results show a high purity of nanostructured silver thin films for sputtering by both argon ions and nitrogen ions, but with some oxygen and carbon contamination. For argon ion sputtering, the content of oxygen and carbon is less than 6.9% and 4.5%, and for nitrogen ion sputtering, less than 4.7% and 3.6%.