Annealing, silver oxide

Fig. 8 Annealing of silver oxide. When the blackish brown silver oxide is moderately heated by a burner the formation of a gas is detectable by the slow blowing up of the balloon. The substance gradually changes its colour to whitish. Finally, the gas can be identified as oxygen with a glowing splint. White shiny silver metal remains in the test tube...

Boron nitride nanocages with silver nanoparticles encapsulated in them have been synthesized by Oku et al." Reaction of urea and boric acid in the presence of silver nitrate produced BN matrices at 700°C. The ingredients were previously dissolved in deionized water and dried consequently to produce a homogenous mixture and annealed separately at 300°C and 700°C. The presence of silver nanoparticles and sometimes silver oxide nanoparticles were detected under TEM (Figure 20.15a) and x-ray diffraction studies. A similar methodology has been developed by Xing et al. in their preparation of zinc oxide- and titanium oxide-encapsulated BN nanocages." ... 

Figure 7 (a, b, d, and e) shows transmission electron micrographs from Pd-Ag films of comparable weight, prepared and annealed at 400°C, and used once to catalyze the oxidation of ethylene at 240°C (40). The structure of this series of alloy films varied consistently with composition. Silver-rich films (e.g., Fig. 7a, 13% Pd) showed extensive coalescence of the crystallites, while at the other end of the composition range (e.g., Fig. 7e,...

It is, of course, well known that metal-semiconductor interfaces frequently have rectifier characteristics. It is significant, however, that this characteristic has been confirmed specifically for systems that have been used as inverse supported catalysts, including the system NiO on Ag described above as catalyst for CO-oxidation. In the experimental approach taken, nickel was evaporated onto a silver electrode and then oxidized in oxygen. A space charge-free counter-electrode was then evaporated onto the nickel oxide layer, and the resulting sandwich structure was annealed. The electrical characteristic of this structure is represented in Fig. 8. The abscissa (U) is the applied potential the ordi-... 

The preparation of rough silver films by vapor deposition results in reproducible and stable surfaces for SERS. For example, deposition of 20-nm Ag films onto Teflon, polystyrene, or latex spheres [29,30] has been performed. These substrates produced strong SERS intensities for various organic adsorbates and good reproducibility between multiple rims. However, vapor deposition can be slow and needs access to a vacuum system. There are also some variables that need to be controlled, such as the film thickness, deposition temperature, and use of annealing procedures. Moreover, unless the experiment is performed under vacuum, the film is exposed to the atmosphere after deposition. Even a brief exposure to the atmosphere results in contamination of the surface and the formation of an inactive oxide layer. 

Ordinary silver bullion processed in air may contain ca 200 ppm oxygen. Commercial silver bullion prepared under nitrogen may contain as Htde as 25 ppm oxygen. During casting some oxygen may be introduced to convert base metal impurities into oxides. Because these oxides do not enter into the soHd solution, they have no effect on the annealing and recrystaUization temperature of the silver critical to the silversmith. 

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