Au, metallic

Electrical Properties. Electrical properties are important for the corrosion protection of chip-on-board (COB) encapsulated devices. Accelerated temperature, humidity, and bias (THB) are usually used to test the embedding materials. Conventional accelerating testing is done at 85°C, 85% relative humidity, and d-c bias voltage. Triple-track test devices with tantalum nitride (Ta2N), titanium—palladium—gold (Ti—Pd—Au) metallizations with 76... 

Gold clusters can be synthesized by three methods reduction of Au(I) compounds, evaporation of Au metal and conversions of Au clusters. 

A rotary apparatus is used for metal evaporation as shown in Fig. 1. Similar equipment is employed for the preparation of organometallics. For Au clusters, Au metal is evaporated from a resistively heated W boat onto an ethanol film, in which the reactants, e.g., AufPAr IX and/or PAr, are dissolved (see Table 1, method B, 8.2.2.2). 

Room temperature CO oxidation has been investigated on a series of Au/metal oxide catalysts at conditions typical of spacecraft atmospheres CO = 50 ppm, COj = 7,000 ppm, H2O = 40% (RH) at 25 C, balance = air, and gas hourly space velocities of 7,000- 60,000 hr . The addition of Au increases the room temperature CO oxidation activity of the metal oxides dramatically. All the Au/metal oxides deactivate during the CO oxidation reaction, especially in the presence of CO in the feed. The stability of the Au/metal oxide catalysts decreases in the following order TiOj > FejO, > NiO > CO3O4. The stability appears to decrease with an increase in the basicity of the metal oxides. In situ FTIR of CO adsorption on Au/Ti02 at 25 C indicates the formation of adsorbed CO, carboxylate, and carbonate species on the catalyst surface. 

The activity of the Au/metal oxide catalysts is extremely sensitive to the method of preparation. The Au/metal oxide catalysts were prepared by the co-precipitating method [1]. During the course of this study, we have determined that the activity and the stability of the catalyst for room temperature CO oxidation were a function of Ph of the solution, temperature of precipitation, aging temperature and time, catalyst wash procedure, and calcination. 

All of the Au/metal oxide catalysts deactivate quickly, under the conditions shown in Figure 4. In addition, the deactivation of the Au/metal oxide catalysts appears to be enhanced in the presence of COj. In support of the theory that increased basicity of the metal oxides leads to lower stability, we carried out COj temperature programmed desorption experiments on the various catalysts. The COj TPD data also confirmed that an increase in the basicity of the metal oxides leads to an increase in the amount of COj adsorption on the catalysts. 

Au/metal oxides are active for low temperature CO oxidation. The activity of the catalysts is very sensitive to catalyst preparation. All the Au/metal oxides tested for room temperature CO oxidation deactivated substantially with time. The deactivation... 

In order to clarify the mechanism responsible of the energy transfer, we investigated the aggregation state of Au atoms and the chemical environment of Er ions in our samples, by performing an EXAFS analysis on the Er + Au 600 °C sample. The experiment evidenced an Au-Au coordination proving the presence of Au metallic aggregates, with an estimated Au-Au distance i = 2.78+ 0.01 A, consistent with the presence of small... 

Au (metal) Resonance effect as function of absorber thickness, isomer shift, Debye temperature of source and absorber... 

Au dissolved in ferromagnetic hosts of Fe, Co, Ni as sources versus Au metal absorber Nuclear Zeeman effect in Au atoms, super-transferred hf fields, // at Au sites... 

Au metal Thick absorber line-shape analysis and interference effects... 

Historically, AuF has been one of the most elusive of all metal halides. At one time it was believed to be impossible to prepare, and theoretical papers speculating on how it might be observed or predicting spectroscopic and structural properties have been published until recently.3075- 1 The existence of AuF has been confirmed by microwave spectroscopy, the sample has been prepared by laser ablation of Au metal in the presence of a F precursor.3082 The gas-phase structure of Aul has also been determined by microwave spectroscopy.3083... 

Preparation of a Typical Au-Acetone Colloid. The metal atom reactor has been described previously. (39,59, 60) As a typical example, a W-A1 0 crucible was charged with 0.5Qg Au metal (one piece). Acetone (300 mL, dried over K2C0 ) was placed in a ligand inlet tube and freeze-pump-thaw degassed with several cycles. The reactor was pumped down to 1 x 10 Torr while the crucible was warmed to red heat. A liquid N2 filled Dewar was placed around the vessel and Au (0.2g) and acetone (80g) were codeposited over a 1.0 hr period. The matrix was a dark purple color at the end of the deposition. The matrix was allowed to warm slowly under vacuum by removal of the liquid N2 from the Dewar and placing the cold Dewar around the reactor. 

The hexafluorouranate(V) with the formula [Au(CO)2]+[UF6] was obtained by dissolving gold powder in liquid anhydrous HF containing UF6 in a CO atmosphere. The crystalline product is stable at room temperature but decomposes on warming above ca. 50 °C. Two decomposition pathways were observed which afford either Au metal, CO gas, and a residue of UF6, or Au metal, a mixture of CO and COF2 gas, and a residue of UF5. The compound was... 

By using Hg-electrode-based junctions, the electrical properties of the highly conjugated units of hexa-pen-hexabenzocoronene (HBC) have been characterized [171]. The HBC unit was anchored to the Au metal surface in an Hg-based junction by a decanonanethiol tether (C19), as depicted in Fig. 9. Comparison of the electrical behaviour of three different junctions, whose interfaces are schematized... 

Table 4.48. Comparison bond lengths Rm and bond orders 6Ab in r 3,four-electron (M = Ir+) versus ri1, two-electron (M = Au+) metal allyl complexes (see Figs. 4.85(c) and 4.86)...

Table 5.52. Cu, Ag, Au metals crystal structures, lattice parameters of their allotropes and calculated densities.

While the combination of currentless and electrodeposition has been reported for different metals such as Pd [41, 179], Pt [196] and Rh [197] on mercaptopyridine SAMs, the scheme has also been applied to thiol-terminated SAMs by Qu and Uosaki [180,198]. Using dithiol SAMs of 1,4-benzenedimethanethiol (HSCH2QH4CH2SH, BDMT) and hexanedithiol (HS(CH2)6SH, HOT) on Au(l 11), Pt and Au were deposited. Interestingly, by adsorbing another thiol, namely decane thiol, onto a deposited Au metal layer, a bilayer was formed, which also demonstrates the potential of this scheme for accessing the third dimension. 

White metal with brdhant metaUic luster face-centered cubic crystals density 10.43 g/cm at 20°C, and 9.18 g/cm at 1,100°C melts at 961.8°C vaporizes at 2,162°C vapor pressure 5 torr at 1,500° C pure metal has the highest electrical and thermal conductive of aU metals, electrical resistivity of pure metal at 25°C 1.617x10 ohm-cm elastic modulus 71GPa (10.3x10 psi) Poisson s ratio 0.39 (hard drawn), 0.37 (annealed) viscosity of hquid silver 3.97 centipoise at 1,043°C thermal neutron absorption cross section 63 1 barns insoluble in water inert to most acids attacked by dilute HNO3 and concentrated H2SO4 soluble in fused caustic soda or caustic potash in the presence of air. 

Triple-track resistor and conductor coupons are made by deposition of Ta2N and Ti-Pd-Au metallization, respectively, on the AI2O3 substrate. This test pattern consists of three parallel meandering lines with 3-mil spaces between lines. Each line is approximately 3-mil wide and has 2.86 X ]0 squares, with an overall length of 8.5 in. The number of squares of insulator between adjacent lines is approximately 3.5 X 10". ... 

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