Papers by Keyword: Silver Film

Abstract: Nanostructure silver films were obtained by dc magnetron sputtering at room temperature. The influences of deposition time on the morphology and optical properties were studied by field-emission scanning electron microscope and UV-vis NIR spectrophotometer. It was found that the optical properties of the nanostructure silver film can be effect by surface morphology. The surface enhanced Raman scattering activities of nanostructure Ag films were demonstrated by methylene blue (MB) as probing molecules while the detection limit of MB was found to be as low as 10^-5 M from this SERS substrate.

Abstract: The microstructure, superhydrophobicity and chemical composition of the moth wing surface were investigated by a scanning electron microscope (SEM), an optical contact angle (CA) meter and a Fourier transform infrared spectrometer (FT-IR). nanosilver film was coated on the wing surface by vacuum evaporation. The wetting mechanism was discussed from the perspective of biological coupling. The moth wing surface, composed of naturally hydrophobic material, is of high hydrophobicity (CA 143~156°) and exhibits complicated hierarchical micro-morphology including primary structure, secondary structure and tertiary structure. The cooperation of hydrophobic material and rough micro-morphology leads to the high hydrophobicity of the wing surface. The wing surfaces coated with 50~1000 nm silver films are still hydrophobic (CA > 110°). The multiple-dimensional rough structure of the wing surface results in the transition of metal silver from hydrophilic to hydrophobic. The moth wing can serve as a bio-template for design and preparation of micro-controllable superhydrophobic surface.

Abstract: A silver film-covered photonic crystal fiber containing different sizes of air holes is proposed to construct the surface plasmon resonance sensor. In this sensor, a nanoscale metal film and analyte can be deposited on the outer side of the fiber instead of coating or filling in the holes of the conventional PCF, which make the real time detection with high sensitivity easily to realize. Moreover, it is relatively stable to the changes of the diameter of air holes, which is very beneficial for sensor fabrication and sensing applications. The finite element method is used to analyze the characteristics of the surface plasmon resonance sensor. And the numerical results show that the resonance wavelength is sensitive to the refractive index of liquid, while the resonance wavelength doesn’t change basically when the diameter of air holes vary.

Abstract: Silver film was fabricated on a glass substrate by electroless plating technique. Plating solution, which also known as Tollen’s reagent, consisted of three main solutions: silver nitrate solution as a silver source, ammonia and sodium hydroxide as pH controllers and D-glucose as a reducing agent. Glass surface was treated by three different methods: HF etching, SnCl₂ activation and SiC paper grinding. After that, a glass slide was immersed in plating solution for 90 minutes at a room temperature. The purpose of this work was to study the effects of different surface treatments on adhesion between substrate and film. X-ray diffraction (XRD) pattern confirmed that the obtained film was a silver phase. Surface morphology of glass slides, before and after plating was investigated by scanning electron microscope (SEM). Moreover, the adhesion of silver film to glass substrate was performed by crosscut test and it was indicated that combined treatment by SiC paper grinding and HF etching was the best surface treatment which provided a good adhesion of film to substrate.

Abstract: PTG materials were prepared using TiO2 as photoconductors, silver palmitate as a reducible silver salt, PHZ as a toner and 2246 as a reducing agent in acrylic acid resin binder. The PTG material was coated onto the PET film and then exposed by UV-meter. Effects of the amount of TiO2 and PHZ on the image properties were investigated by means of ultraviolet-visible spectroscopy (UV) and transmission density meter. The formation of silver image was confirmed from the absorption peak around 430nm and X-ray photoelectron spectroscopy (XPS) analysis. The results show that the optimum content is that PHZ of 0.5g and titanium dioxide of 0.03g. The Atomic Force Microscopy (AFM) showed that the triangle-like grains with size of 43nm and height of 10nm grew uniformly on the surface of the exposed PTG film.

Abstract: Two types of low-emissive coatings were deposited onto glass substrates by magnetron sputting method, which were designed as Ag and TiO2/Ni-Cr/Ag/Ni-Cr/TiO2. The transmittance and thickness of the samples were measured by TH1901 spectrophotometer and NKD-8000V ellipsometer. Fourier transform infrared spectrometer (FTIR) was employed to detect the low emissivity properties, it demonstrated that the silver-based multilayer coatings showed an efficient heat isolation due to their low emissivity properties. And they had a good performance in the visible range compared to the single Ag layer according to the transmittance spectra as well. The surface morphology of the samples was investigated by scanning probe microscope (SPM), it was determined that the Ag layer formed a homogeneous grain size when deposited onto the Ni-Cr layers.

Abstract: Silver films were prepared on the glass substrate by electron-beam vapor deposition. The reflectivity of the Ag thin film was measured by a Perkin-Elmer Lambda spectrophotometer in the wavelength region of 450-680 nm. The experimental measurements of reflectivity were validated with the numerical results using the Essential Macleod software. The surface topology and microstructure of the film were examined by means of atomic force microscope (AFM). The effects of the thermal and humidity on the reflectivity of the Ag film were examined by the environmental test. Nanoindentation tests were employed to determine the hardness of the film. The measured hardness of the Ag thin film was found to depend on the penetration depth.

Abstract: A series of Ag films with different thicknesses were prepared on polyethylene terephthalate (PET) substrates under identical conditions by thermal evaporation. The effect of the thickness on the optical and electrical properties of the films was studied. The morphology of the samples was investigated by atomic force microscopy (AFM). The optical and electrical properties were measured by spectrophotometer and four-point probe method, respectively. The experimental results show that the reflectance increases, while transmittance and resistivity decrease with the increase of the thickness. There exists a critical thickness of the film and it is 75 nm in this experiment. The optical and electrical properties of Ag films on PET substrates with thickness larger than critical thickness, are close to those of the conventional bulk silver. The resistivity of the 150-nm film is 3.0±0.2 μΩ•cm, which is lower than that of the 250-nm Ag film grown on BK-7 glass substrates.

Abstract: A silver film was deposited on silicon wafer by DC unbalance magnetron sputtering system. The temperature dependence of the silver film was investigated. The spectroscopic ellipsometry (SE) with the heating of sample stage (HTC100) was employed for the in situ SE measurement under annealing cycles of the sample from room temperature to 300°C in dry nitrogen gas. The results show that the pseudo dielectric constants (<ε1>, < ε2>) of the sample varied with an annealing temperature. The real part of pseudo dielectric constant (<ε1>) of annealed Ag film was slightly changed and the imaginary part (< ε2>) was strongly increased at a photon energy below the optical band gap (3.5-4.5 eV). Furthermore, the pseudo dielectric constant of imaginary part at low energy region was changed due to the enhancement of crystallinity of Ag film at 300°C. All measured SE spectra were fitted by Drude-Lorentz optical model, the scattering time and resistivity were obtained.

Abstract: To prepare the nano-scale silver carboxylate emulsions and investigate their applications in the preparation of nano-scale silver films, the silver citrate emulsion was synthesized through the reaction of silver nitrate with sodium citrate in the presence of polyvinylpyrrolidone (PVP) as a surface modification agent in water. The emulsion was coated onto the surface of the PET substrate to form a thin latex layer of silver citrate. And this was followed by drying at about 100 °C. Then, the silver citrate thin film was deoxidized by aqueous ascorbic acid. Finally, a translucent silver thin film was formed on the surface of the PET substrate. Properties of the silver citrate emulsion and the silver film on the PET were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), laser particle size analysis, scanning electron microscopy (SEM), thermogravimetry(TG) ,UV-visible absorption spectroscopy, atomic force microscopy(AFM) and digital multimeter analysis. It was found that the silver citrate particle surface-modified by PVP has a nano-rod structure and homogeneous size distribution. The nano-rod was about 20 nm in diameter and 200 nm in length. For the UV-visible absorption spectrum of the thin film exhibited an absorption peak at 430 nm, the silver thin film prepared on the surface of the PET substrate was a typical nano-scale sliver film. Measurements of the sliver thin film at room temperature indicated that the silver film was electrically conductive, and the surface resistance was 2.42 k5/cm.