Kinetics of picosecond laser treatment of silver nanoparticles on ITO substrate

In this work, the effect of ITO substrate on Ag NP size, morphology and photoinduced absorption depending on the time of 30 ps laser treatment were explicitly studied. Silver nanoparticles with an average diameter of ∼40 nm supported on indium tin oxide (ITO) were irradiated with a tightly focused pulsed laser (doubled frequency beam) at 532 nm. The size transformation of silver nanoparticles induced by a single pulse of Nd:YAG laser (λ = 532 nm, pulse width = 30 ps) was directly observed by an electron scanning microscopy (FE-SEM) on indium tin oxide surface. Simultaneously the change in the absorption and the corresponding derivatives are also presented. These morphological changes are accompanied by a significant change in the optical absorption properties of the array. This study demonstrates that picosecond laser irradiation is an excellent technique to operate and control the properties of nanostructured materials on solid supports.     

Characteristics of ITO films deposited on a PET substrate under various deposition conditions

ITO films, with a thickness of 150 nm to 160 nm, were deposited on an unheated hard coated PET substrate or non-alkali glass substrate via dc magnetron sputtering. Depositions were carried out under the following various conditions: total gas pressure (P_tot), dc sputtering power, target — substrate (T-S) distance, and O₂ or H₂ addition ratio. The ITO coated on the PET substrate showed relatively lower resistivity than that of the ITO coated on a glass substrate. Relatively small changes in the resistance (ΔR/R₀=0.4) of the films were obtained for each deposition condition for the ITO/PET deposited under a sputtering power of 70 W, P_tot of 0.5 Pa, and T-S of 50 mm. It has been confirmed that the results of the electrical property showed concurrence with the results of the bending test. Specifically, the films that have a good electrical property showed only a small change in resistance to the increasing cycle number for each deposition condition. Therefore, it can be assumed that the increased resistance of the ITO films could be due to the formation of micro defects such as micro-cracks and the micro detachment of the ITO film from the flexible PET substrate.     

Properties of ITO films deposited with different conductivity ITO targets

Characterizations were performed for ITO films deposited using different erosion ratios for the target surface and different conductivity targets. The ITO films were deposited on unheated substrates using de magnetron sputtering with different conductive targets, and then the films were post-annealed in a H₂ atmosphere in a vacuum chamber. By increasing the target erosion ratio, the optimal O₂ addition ratio to obtain the lowest resistivity was decreased. For the post-annealed films, the resistivity of the ITO films consistently deceased with an increasing T_a, which can be attributed to the increase of the carrier density. By increasing the target erosion ratio, the XRD patterns of the post-annealed ITO films showed a higher peak intensity on the (222) plane than that on the (400) plane, implying that the oxidation of the ITO films was enhanced.     

The characteristics of gold films deposited on ceramic substrate

A large quantity of gold (approximately 10 tonnes yearly) is consumed, all over the world, just to decorate ceramic and glassware. Due to their advanced chemical stability gold films are used for different high technology applications. The technologies for obtaining the best “liquid bright gold” were intensively studied, but the quality of the decor coatings (films) were empirically assessed. We proposed a scientific investigation of the characteristics of gold films, deposited on ceramic substrates, from “liquid bright golds”. The composition of the film has been determined by EDS (Energy Dispersive X-ray Spectrometry). The distribution of the elements was determined at the surface of the film and in cross-section. The surface distribution of the elements was uniform. The diffusion process of the film into substrate and the migration of the substrate elements at the interface region and into the film have been highlighted.     

Study on adhesion and electro-optical properties of ITO films on flexible PET substrate

High-quality ITO films on flexible PET substrate were prepared by RF magnetron sputtering at low deposition temperature with different Ar gas sputtering pressure.Adhesion and electro-optical properties of ITO films were investigated as a function of Ar partial pressure.The sputtering conditions provide very uniform ITO films with high transparency (＞85% in 400-760 nm spectra) and low electrical resistivity (1.408×10-3-1.956×10-3 Ω·cm).Scratch test experiments indicate that there is a good adhesion property between ITO films and PET substrate, the critical characteristic load increases from 16.5 to 23.2 N with increasing Ar sputtering pressure from 0.2 to 1.4 Pa.     

铝基板上沉积氮化铝薄膜的制备及特性分析

采用直流反应磁控溅射方法,在铝基板上制备了AIN薄膜.利用X射线衍射仪、带能量色散谱仪的扫描电子显微镜、阻抗特性测试仪、椭圆偏振光谱仪、大荷载划痕仪等对薄膜特性进行测试,分析了不同溅射工艺条件对生长薄膜的影响.结果表明,获得了化学计量比一致、结合力良好、击穿场强达112V/μm的(100)多晶择优取向AIN薄膜.     

Fabrication of YBCO films on Ag substrate by TFA-MOD method

Biaxial aligned YBCO films have been successfully deposited on Ag { 110 } (110) textured polycrystalline substrates by metal-organic decomposition (MOD) method using Trifluoroacetate Salt (TFA). The influence of firing temperature and Ag surface defects on phase purity and texture, surface morphology of YBCO films was studied. Holding temperature at 900℃ for 30 rain benefits to improve orientation and connectivity of YBCO films. The surface of YBCO films deposited on unpolished Ag substrate has many holes and stripes, which are parallel to the rolling stripe on Ag substrates. To eliminate the rolling stripe on the Ag surface, Ag substrates were polished prior to films deposition. The film grown on polished Ag substrates has a smooth surface and good connectivity of grains without parallel stripes. The YBCO films have an onset of transition around 90K and critical current densities of 15000 A/cm^2.     

Adherent nanocrystalline diamond coatings deposited on Ti substrate at moderate temperatures

Microwave plasma enhanced CVD deposition of adherent nanocrystalline diamond coating on pure Ti substrate was studied at a moderate temperature and with a wide range of CH₄ concentrations. Under low CH₄ concentrations, the adhesion failure of diamond coatings is primarily observed at the titanium carbide–substrate interface. Under higher CH₄ concentrations, the diamond coating debonding occurs both at the diamond–carbide interface and carbide–substrate interface. On the whole, the nucleation density, nucleation rate and adhesion strength of diamond coatings grown on Ti substrate are enhanced with increasing CH₄ concentrations. Synchrotron X-ray Laue micro-beam diffraction characterization of the underlying Ti substrate reveals that a microstructure coarsening occurs after hydrogen plasma etching, whereas the hydrogen penetration is effectively mitigated under super high CH₄ concentrations.     

Laser stripping of Ag shell from Au@Ag nanoparticles

Metallic nanoparticles (NPs) are a class of important materials with widespread applications due to their chem-ical stability and high photothermal conversion e...     

Superheating of Ag nanoparticles embedded in Ni matrix

Nanometer-sized Ag particles embedded in a Ni matrix were prepared by using melt spinning. The uniformly distributed Ag nanoparticles with a mean size of 30 nm exhibit a cube–cube orientation relationship with the Ni matrix, and some Ag nanoparticles are surrounded by {111} and {100} low-energy interfaces. Differential scanning calorimetry (DSC) and in situ X-ray diffraction (XRD) analysis results indicate that the Ag nanoparticles can be substantially superheated above the equilibrium melting point (T₀) of the bulk Ag, as much as about 70 K above T₀ in the DSC measurement at a heating rate of 20 K/min. The superheating phenomenon is reproducible upon several heating/cooling cycles. In situ XRD results also indicate that the smaller the Ag particle, the higher the superheating. Our observations can be qualitatively interpreted with thermodynamic considerations.     

Photoinduced electron transfer at an ITO/C60 trapped in a thin polypyrrole film interface

The photoelectrochemical properties of C₆₀ entrapped in thin, functionalized polypyrrole films coated on indium-tin oxide (ITO) electrodes have been examined. A stable photocurrent is observed in the presence of an irreversible electron donor (ascorbic acid) in solution. Results suggest the coexistence of monomers and aggregates of C₆₀ in the polymeric matrix.     

The effects of substrate compositions on adhesion of diamond films deposited on Fe-base alloys

Diamond deposition on a series of ferrous alloy substrates has been examined in a microwave plasma enhanced chemical vapor deposition reactor. The results show that the nucleation, growth, and adhesion properties of the diamond are strongly dependent on the types and relative concentrations of the alloy elements in the substrates. Along with high nucleation densities, continuous and adherent diamond films have been successfully fabricated on the Al-modified alloy substrates, even in the absence of inter-layers or nucleation enhancing surface pre-treatment. The mechanism is preliminarily clarified regarding the delicate competition and balance between the base metal and the alloying elements in terms of their activation and deactivation ability on catalyzing graphite formation during deposition process.     

Synthesis and characterization of Ag doped Cu nanoparticles

The synthesis of Cu_100−xAg_x (0.05 at.% < x < 0.30 at.%) nanoparticles using an evaporation–condensation process has been studied. Particular attention has been paid to the composition of the as-prepared powders. Compared to the master alloy, systematic enrichment in Ag of the particles is observed at the beginning of the synthesis but a continuous decrease in the Ag content of the powders is observed during the process. Even though, after de-agglomeration, the chemical composition of the powders is, in average, homogeneous. We have shown that optimized synthesis conditions give spherical particles with a mean diameter of 50 nm and a reasonable yield rate.     

Effect of heating cycle on the structure of Ag films deposited over porcelain substrates

Silver films were deposited over porcelain substrates by using flexible adhesive transfer layers. These films were produced in order to use porcelain utensils over household induction heating plates. Mixtures of different glass ceramic powders with silver powder are used to prepare the self-transfer patterns. These patterns are deposited over porcelain substrates and sintered using different heating cycles. One defect observed in such films is the presence of porosity either at the Ag/porcelain interface or inside the Ag film structure. While lower sintering temperatures produce less porosity, the microstructure of the Ag layer at lower temperatures is no longer composed of a contiguous network of large silver agglomerates. Consequently, the heating capability of the layer through electromagnetic induction is affected. Finally a sintering cycle is proposed for which the film properties are least modified with a minimum level of porosity.     

Photoinduced absorption and nonlinear optical properties of disubstituted polyacetylenes: Theory

In this paper, we summarize results of our recent large-scale correlated calculations of nonlinear optical spectra and photoinduced absorption (PA) spectra of phenyl-disubstituted polyacetylenes (PDPA). Calculations were performed on oligomers of PDPA's using correlated-electron Pariser–Parr–Pople (P–P–P) model and configuration interaction (CI) methodology. Computed PA spectra are compared with the recent experiments of Korovyanko et al., and good agreement is obtained between the two.     

Synthesis and magnetic properties of nickel nanoparticles deposited on the silicon nanowires

Nickel (Ni) nanoparticles with sizes of ∼35 nm were deposited on the surface of silicon nanowires (SiNWs) by electroless plating technique. The magnetic properties of Ni/SiNWs were investigated. The blocking temperature (T_B) of 370 K was obtained and confirmed by field-cooled (FC) and zero-field-cooled (ZFC) plots. The M-H hysteresis loops from 5 K to 400 K were measured. The saturation magnetization value was ∼4.5 emu/g and the coercivity was ∼375.3 Oe for the loop at 5 K, respectively. While for the loop at 400 K, these values were of ∼2.6 emu/g and ∼33.3 Oe, respectively. The temperature dependence of coercivity followed by the relation H_C(T) = H_C0[1 − (T/T_B)^1/2], indicating a superparamagnetic behavior. The magnetization of superparamagnetic grains in a magnetic field H was better described by Langevin function at 400 K. These novel magnetic properties of Ni/SiNWs were possibly attributed to the paramagnetic defects on the surface of SiNWs.     

Copper electrocrystallization on a heterogeneous silver Ag(111) substrate

Comparison of the results obtained by Fischer for copper electrocrystallization on a homogeneous substrate with the results obtained here indicates that there are well-defined differences in the calculated valuse of the kinetic parameters describing the electrocrystallization process in these two cases. Metal nucleation on a heterogeneous substrate is associated with the necessity of achieving a supersaturation of deposited-metal adatoms sufficient to ensure the formation of a stable crystallization nucleus. In the initial stage of electrocrystallization, there are a number of differences between the process taking place on the heterogeneous substrate and that taking place on the homogeneous substrate.     

Microwave absorption properties of TiN nanoparticles

TiN nanoparticles with an average diameter of 15 nm or so were prepared by the reaction of spongy Ti and NH₄Cl at about 530 °C. The electromagnetic parameters of the TiN nanoparticles/wax composite were measured by a coaxial line method. The nanoparticles exhibit good microwave absorbing ability owing to dielectric loss, and the measured reflection loss reaches a minimum value of −16.1 dB at 13.8 GHz. The interfaces between nanocrystalline TiN and the thin amorphous TiO₂ layer on the TiN surface contribute dominantly to the high permittivity and good microwave absorbing properties.     

Improved sensing performance of WO3 nanoparticles decorated with Ag and Pt nanoparticles

Gas sensors built with metal oxide semicon-ductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explo-sive and...     

Large scale synthesis of fishbone-like ZnS nanostructures using ITO glass as the substrate

Fishbone-like ZnS nanostructures have been successfully synthesized by using a simply thermal evaporation of ZnS powders using ITO glass as the deposition substrate. Scanning electron microscope (SEM) images indicated that as-grown ZnS nanostructures consisted of main spines with lengths of several micrometers and numerous secondary branches with widths of 50 to 100 nm and lengths of about 500 nm distributed on both sides of the spines. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) results reveal that both the spines and the branches grew along the [0 0 0 1] directions. A possible growth mechanism was proposed to explain the formation of complex nanostructures.