Papers by Keyword: Au

Abstract: Neural probe array is used for neural recording and simulation applications. It will be implanted into the motor cortex of a paralytic human to control robotic arm and perform tasks such as grasping an object. The major components are silicon (Si) probes, Si platform, application-specific integrated circuit (ASIC), polyimide flexible cable and wireless IC. In-plane Si probes are inserted into the Si platform to form a three-dimensional (3D) probe array. Wirebonding technique is used to integrate the ASIC and the probe array. Pad finishes play an important role in wire bonding as it would affect the reliability of the electrical connections. As such, the focus of the paper will be on the evaluation and characterization of an electroless nickel immersion gold (ENIG) pad finishing and its bonding parameters for wirebonding application. ENIG pad having a 0.1-µm gold (Au) thickness combined with an additional Au stud and wirebonding temperature of 200 °C are found to have comparable wirebonding capabilities as a 0.3-µm thick Au finishing pad. The wire pull test result and SEM observation between the ENIG and Au finishing pad at different bonding parameters were presented and discussed.

Abstract: The complexity of sea environment and the uncertainty of AUV model lead to difficulties of heading control. It is difficult to satisfy its requirement for high accuracy and fast speed through the use of a single control method, based on the peculiarity of AUV and the existing problem of control, We propose a fuzzy-PID control method based on a grey model, which combines fuzzy control with PID control, Our simulations confirm that our method provides higher robustness and adaptive property than regular PID, it is suitable for the use of AUV in complexity sea environment.

Abstract: With density functional theory, the structural and electronic properties of Au3 and Au2M (M=Ag, Cu, Pd and Pt) clusters have been studied. The structural results indicate that by substituting one Au atom with M atom, the corresponding geometries are changed slightly. To investigate the electronic properties, bonding properties and highest occupied molecular orbital (HOMO) were observed. It is found that most trends in Au2Pd and Au2Pt are similar and it also happens in the other two doped clusters. In addition, the calculated mulliken overlap populations suggest that doping modify the localized electron between Au and Au atom. It is also found that the contributions from various atoms on HOMO and energies of HOMO are changed. These may make difference in the adsorption of clusters.

Abstract: Au-TiO₂ composite photocatalysis material was fabricated by the photodeposition method. The SEM and TEM images demonstrate that Au-TiO₂ NPs are with inerratic geometry and their diameters are in the range of 10 nm to 20 nm. The UV-vis spectra shows the strong peaks in 200-400 nm and near 550 nm which are attributed to the characteristic absorption peak of TiO₂ and the strong surface-plasmon-resonance of Au NPs, respectively. Under visible light irradiation, the phenol degradation dynamics constant on Au-TiO₂ was 0.008 min-1 which was 4 times of that on Degussa P25. The effects of Au amount on the photocatalytic capability of Au-TiO₂ were also investigated.

Abstract: Graphene oxide (GO), an oxygen-rich carbonaceous layered material, is produced by the strong oxidation of graphite. The GO aqueous suspension is very stable and can be fabricated to porous GO aerogels by a green method, unidirectional freeze-drying technology. GO shows catalytic activities in both solution and solid state. It can also act as reductant or oxidant depending on the reaction patterns. The product of the reaction was analyzed and the component change of the graphene oxide (GO) was monitored by x-ray photoelectron spectrometer, scanning electron microscopy and transmission electron microscopy. The results confirm that GO not only acts as the reactant in the reaction, but also as the catalyst to catalyze the reaction.

Abstract: This study demonstrates a novel technique for the fabrication of ordered arrays of Au rich nanoparticles on a Si substrate. Si substrates, with their native oxides intact, are pre-patterned using nanoindentation to create regions on the surface that readily alloy at higher temperatures with a thin thermally evaporated Au layer. Larger Au rich particles are observed to form at the indentation sites after high temperature annealing in an inert atmosphere. After mechanical wiping, the Au rich particles lying within the indentation sites remain while almost all the particles on the native oxide surface are readily removed. Using PECVD techniques, multi-prong Si nanowires are shown to grow from the remaining arrays of Au rich particles.

Abstract: Acid-activated by H₂SO₄ was applied to modify bentonite. Acid-activated bentonite supported Au catalyst was prepared by deposition-precipitation and compared with SiO₂ supported one. CTAB was used to modify the surface of acid-activated bentonite. Au-Ce/bentontie catalyst was prepared by adding Ce into catalyst as assistant. CO oxidation was used to evaluate the catalytic activity of samples. These samples were characterized by BET, XRD, ICP and CO-TPD. The activity results showed that Au/Bentonite was more active than Au/SiO₂. The BET results showed that the surface area and pore volume of acid-activated bentontie had a substantial improvement. Using the bentontie acid-activated by 30wt%H₂SO₄ as supporter，the Au-Ce catalyst has a better catalytic performance than Au catalyst.

Abstract: Au/Co₃O₄ catalysts were prepared by a co-precipitation method and characterized by inductively coupled plasma-atomic emission spectrometry (ICP-AES), transmission electron microscope (TEM) and X-ray diffraction (XRD). The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol was investigated over Au/Co₃O₄ catalysts using molecular oxygen as oxidant. These catalysts showed higher activities as compared to the pure Co₃O₄ under the same reaction conditions_.

Abstract: Classical molecular dynamics simulation was used to investigate the structure, melting and mechanical properties of Au nanowires encapsulated in single-walled carbon nanotubes (SWCNT). A possibility of synthesizing controlled Au nanowires was firstly studied by encapsulating small clusters into CNTs with suitable diameters. The nanowires with multi-shell structure of cylindrical symmetry are predicted as a consequence of spontaneous and confined coalescence of gold clusters. The investigation of melting temperature and behavior of a gold nanowire with multi-shells in a carbon nanotube (CNT) showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behavior of freestanding Au nanowires, the melting of Au nanowires enclosed in CNTs with tube diameters (D) in the range of 1.08 nm < D < 2.09 nm investigated here was found to initiate from the center layers. Finally, the deformation behavior of the gold-filled single-walled carbon nanotube was simulated under axial compression. The results show that the buckling strength of the Au-filled carbon nanotube is increased compared with that of a hollow tube, and is similar to the case of filling with gases or fullerenes. The interactions between filling elements and the carbon wall help restrain the collapse of the tube. With Au-filling, the filled tube experiences an elastic-inelastic transition, somewhat like the behavior of metals, which is different from the cases when it is filled with gases or fullerenes, particularly for low filling density.

Abstract: This study investigated the applicability of TiO₂/Au (or TiO₂/Ag) composite particles, which probably have the plasmon resonance effect, on FTO-glass substrate of the working electrode of a DSSC. The dry particle coating technique was utilized to coat the surfaces of TiO₂ particle with nano-sized Au (or Ag) powder particles. A layer of TiO₂/Au (or TiO₂/Ag) composite particles was deposited on the FTO-glass substrate of the working electrode, and it was then sintered in a high-temperature furnace. The working electrode covered with a TiO₂/Au (or TiO₂/Ag) thin film was kept immersed in a solution of N-719 (Ruthenium) dye for 12 h. Finally, the DSSC was assembled, and the short-circuit photocurrent; the open-circuit photovoltage, and the power conversion efficiency η of DSSC were measured using a home-made I-V measurement system. This study also examined the effects of the mass ratio of TiO₂ to Au (or Ag) and the duration of dry coating on the η of the DSSC. If the duration of dry coating is adequate, the η of the DSSC with TiO₂/Au (or TiO₂/Ag) composite particles increased with increase in the percentage of Au (or Ag) in the composite particles. Most importantly, this study shows that the power conversion efficiency η of the DSSC with a film of TiO₂/Au (or TiO₂/Ag) on the working electrode always exceeds that of the conventional DSSC due to presence of the Schottky barrier, which is probably created in the TiO₂/Au (or TiO₂/Ag) composite particle.