贵州省隆晴锑矿冶炼炉渣中锑和金分布规律、赋存状态与潜在价值

冶炼炉渣综合利用对发展循环经济,建设绿色矿山具有重要意义。本文从晴隆锑矿的矿石类型、冶炼工艺分析入手,对晴隆锑矿炉渣进行了分类,并对炉渣中Sb和Au的含量、品位以及赋存状态进行了研究,目的是为晴隆锑矿冶炼渣的开发利用提供依据,该研究结果对其他矿山亦有借鉴意义。     

Electro-oxidation of formate-based solutions on Au/Pd core–shell nanoparticles – Experiment and simulation

Au/Pd core–shell nanoparticles (NPs) were employed to study electro-oxidation mechanism of formate-based solutions. A series of combined studies including Raman spectroscopy, electrochemical stripping analysis, and computational simulations were conducted to understand electro-oxidation of formate-based solutions on the Au/Pd NPs. Compared to the commercial Pd black, the Au/Pd NPs showed superior catalytic activities, especially when using concentrated formate solutions. CO stripping test in conjunction with in situ Raman studies showed a lower oxidation potential (0.6 V vs. Ag/AgCl) of CO on the Au/Pd NPs than the Pd black (>0.6 V). This indicated a strong electronic coupling between Au and Pd in the core–shell NPs which could enhance the oxidation of formate species. In addition, theoretical studies suggested lower formate and hydroxyl coverages at the same applied potential for the Au/Pd NPs than the Pd black in the formate-based solutions, shedding lights on their superior formate-oxidizing ability.     

Phase reaction of Au/Sn solder bonding for GaN-based vertical structure light emitting diodes

Au/Sn solder bonding on Si substrates was used to fabricate the GaN-based vertical structure light emitting diodes (VSLEDs). The phase reaction of Au/Sn solder under different bonding conditions was investigated by the measurement of electron back scattering diffraction (EBSD), and the characteristics of VSLED were analyzed by scanning acoustic microscope (SAM), Raman scattering, current-voltage (I-V) and light output-current (L-I) curves. After the bonding process, horizontal stripes of Au/Sn phase (δ phas...     

制备条件对Au/TiO_2液相氧化反应活性的影响

采用沉积-沉淀法制备纳米级Au/TiO_2催化剂,以葡萄糖液相催化氧化制葡萄糖酸为探针反应,考察了催化剂制备条件对Au/TiO_2活性的影响,并利用TEM、XRD和XPS等方法对催化剂进行了表征。结果表明,Au/TiO_2对葡萄糖液相氧化反应的催化活性与催化剂的制备条件密切相关,纳米金的颗粒尺寸不是决定催化活性的惟一因素,金在催化剂中的价态对催化活性有重要影响。     

One-step synthesis and characterization of single Au microballs through self-organization

Uniform single microballs consisted of Au particles have been firstly prepared by a simple, fast, one-step method using o-phenylenediamine (o-PD) as a reducing agent at room temperature and characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. It has been demonstrated that the initial o-PD/Au molar ratio is a key factor to control the formation and size of single Au microballs through self-organization of Au particles using simultaneously formed o-PD oligomers with phenazyl-like structures as molecular linkers.     

Electromigration effects on intermetallic growth at wire-bond interfaces

At a bimetallic interface, excessive intermetallic growth can cause device failure. For each intermetallic phase, a direct current flowing normal to the interface can change its thickening rate, increasing the rate for current in one direction and decreasing it for the reverse direction. In this paper, we present electrical resistance measurements on single wire-bond/bond-pad interfaces under the influence of current. Resistance increases are correlated with the growth of intermetallics observed in cross section of the wire bonds, providing a sensitive probe of microstructural evolution. The form of resistance change is clearly altered under applied current and depends on polarity. The resistance changes demonstrate key aspects of the effects of electromigration on intermetallic growth, but a fully quantitative interpretation of the changes is hampered by the appearance of more than one intermetallic phase and by the development of voids.     

Supported gold catalysis derived from the interaction of a Au–phosphine complex with as-precipitated titanium hydroxide and titanium oxide

Supported gold catalysts derived from interaction of a Au–phosphine complex Au(PPh₃)(NO₃) (1) with conventional titanium oxide TiO₂ and as-precipitated titanium hydroxide (*, as-precipitated) have been characterized by means of XRD, XPS, EXAFS, and CP/MAS–NMR. The Au complex 1 was supported on TiO₂ and without loss of Au–P bonding at room temperature. The Au complex 1 on TiO₂ was readily and completely decomposed to form metallic gold particles by calcination at 473 K, whereas only a small part of the complex 1 on was transformed to metallic gold particles. By calcination of 1/ at 573 K the formation of both metallic gold particles and crystalline titanium oxides became notable as evidenced by XRD, XPS and CP/MAS–NMR. The mean diameter of Au particles in 1/ calcined at 673 K was less than 30 Å as estimated from Au(2 0 0) diffraction, which was about one-tenth of that for the corresponding 1/TiO₂. Thus the as-precipitated titanium hydroxide was able to stabilize the Au complex 1 to lead to the simultaneous decomposition of Au complex and . The catalyst 1/ calcined at 673 K afforded remarkably high catalytic activity for low-temperature CO oxidation at 273–373 K as compared to the catalyst 1/TiO₂.     

Investigation of the preparation and activity of gold catalysts in the total oxidation of n-hexane

The factors affecting the preparation of Au/TiO₂ catalysts and their activity in the total oxidation of n-hexane were investigated. The mechanism of gold deposition–precipitation is discussed through comparison of the samples prepared by this method and others prepared by anion adsorption method. The influence of the pH and of the origin of TiO₂ support used are additionally addressed. The difference of gold dispersion observed between the two methods is attributed to a difference of mobility of the gold precursors during the thermal treatment rather than to a difference of dispersion over the uncalcined samples. The mechanism of gold deposition–precipitation actually involves the reactions of gold hydroxy-chloride species with the surface. Another part of the work, thus, concerned the use of the deposition–precipitation method to prepare a Au/MnO₂ catalyst. It is shown that the activity of γ-MnO₂ is directly proportional to its surface area and that the deposition–precipitation procedure decreases the surface and activity of MnO₂. However, the deposition of gold allows to avoid a too deep sintering of γ-MnO₂ and, thus, helps to somehow preserve its activity.     

Synthesis of Au-catalyzed silicon nanowires by hydrogen radical-assisted deposition method

Silicon nanowires (SiNWs) catalyzed by gold (Au) nanoparticles were synthesized from silane gas by the hydrogen radical-assisted deposition method. The gold particles used as catalyst were fabricated from an evaporated Au film on a glass substrate by hydrogen radical treatment and the structural properties were estimated. Subsequently, large quantities of SiNWs with various crystal diffraction phases were synthesized on this substrate. The SiNWs were whisker-like and were typically several microns long with diameters of tens of nanometers near the bottom and several nanometers at the top. Hydrogen radical treatments for fabricating catalyst particles and the subsequent deposition method for synthesizing SiNWs are proposed and discussed.     

In situ diffraction studies of electrode surface structure during gold electrodeposition

Surface X-ray scattering (SXS) in transmission geometry provides a valuable tool for in situ structural studies of electrochemical interfaces under reaction conditions, as illustrated here for homoepitaxial electrodeposition on Au(1 0 0) and Au(1 1 1) electrodes. Employing diffusion-limited deposition conditions to separate the effects of potential and deposition rate, a mutual interaction between the interface structure and the growth behavior is found. Time-dependent SXS measurements during Au(1 0 0) homoepitaxy show with decreasing potential transitions from step flow to layer-by-layer growth, then to multilayer growth, and finally back to layer-by-layer growth. This complex growth behavior can be explained within the framework of kinetic growth theory by the effect of potential, Cl adsorbates and the Au surface structure, specifically the presence of the surface reconstruction, on the Au surface mobility. Conversely, the electrodeposition process influences the structure of the reconstructed Au surface, as illustrated for Au(1 1 1), where a significant deposition-induced compression of the Au surface layer as compared to Au(1 1 1) surfaces under ultrahigh vacuum conditions or in Au-free electrolyte is found. This compression increases towards more negative potentials, which may be explained by a release of potential-induced surface stress.