Metallic particulate films

Experimental systems used in the chemical generation and in situ optical monitoring of nanosized metallic particulate films are illustrated in Fig. 90. A precursor gas (CO, for example) may be injected in the arrangement shown in the upper part of Fig. 90, while that shown in the lower part of Fig. 90 permits the... 

Available information on the generation of metallic particulate films in the different membrane-mimetic compartments is summarized in Table 5. 

The experimental set-up used in the generation and in situ monitoring of semiconductor particulate films is identical to that used for nanosized, metallic, particulate films. Evolution of a nanocrystalline particulate film, illustrated by the formation of sulfide semiconductor particulate films (Fig. 110), has been discussed in terms of the following steps [639] ... 

Available results on the preparation, characterization, and utilization of metallic and catalytic particles (Sect. 3), semiconductor particles and particulate films (Sect. 4), conductors and superconductors (Sect. 5), magnetism and magnetic particles and particulate films (Sect. 6), and advanced ceramic materials (Sect. 7) will constitute the main body of the monograph. An attempt will be made to cover these materials exhaustively. 

Metallic and Catalytic Particles and Particulate Films in Membrane-Mimetic Compartments... 

It is important to state the difference between particles and particulate films at the onset of this section. Particles are separate nanometer- to micron-sized colloids dispersed in solution. Physically interconnected colloidal metal particles constitute a particulate film which may be supported by a monolayer floating on an aqueous subphase or be deposited on a solid substrate. 

Table 5. Metallic and catalytic particles and particulate films in membrane-mimetic compartments... 

Negatively charged monolayers floating on an aqueous silver nitrate solution Ag Metallic silver particulate films generated electrochemically at monolayer surfaces could be transferred at any stage of their development to solid substrates 566, 567... 

CdSe particulate films could be transferred to solid 645 supports at any stage of their growth scanning tunneling spectroscopy on a conducting substrate indicated an n-type metal-insulator-semiconductor (MIS) junction behavior... 

K. Aslan, M. J. Previte, Y. Zhang, and C. D. Geddes. Metal-Enhanced Fluorescence from Zinc Particulate Films The Journal of Physical Chemistry C, In Press,... 

In another similar example nanocomposite was formed in a polyurethane matrix. Solvent soluble polyurethane had pyridine groups attached which formed complexes with metal salts. Films were then formed and subjected to a reducing agent in order to produce particulate metal filler. In this case the distribution of the filler which was formed was not uniform because the filler had tendency to aggregate (even though it was chemically attached to the matrix prior to the reduction). The following were factors controlling size and shape of these metal particles ... 

Because the corrosion resistance of lead and lead alloys is associated with the formation of the protective corrosion film, removal of the film in any way causes rapid attack. Thus the velocity of a solution passing over a surface can lead to significantly increased attack, particularly if the solution contains suspended particulate material. Lead is also attacked rapidly in the presence of high velocity deionised water. The lack of dissolved minerals in such water prevents the formation of an insoluble protective film. In most solutions, lead and lead alloys are resistant to galvanic corrosion because of the formation of a nonconductive corrosion film. In contact with more noble metals, however, lead can undergo galvanic attack which is accelerated by stray electrical currents. 

Fogging reduction of the lustre of a metal by a film or particulate layer of corrosion product, e.g. the dulling of bright nickel surfaces. 

Either particulate sol or polymeric sol has been used for thin film coatings. The polymeric sol was fabricated by partial hydrolysis of corresponding metal alkoxide. If the rate of hydrolysis or condensation is very fast, then some kinds of organic acids, beta-dicarbonyls, and alkanolamines have been used as chelating agent in sol-gel processes to control the extent and direction of the hydrolysis-condensation reaction by forming a strong complex with alkoxide. [2]. 

Recent considerations of metal UPD on semiconductor surfaces suggest that light-assisted processes gain much significance in the relevant technology. The use of photoinduced UPD as an approach for the preparation of compounds and composite semiconductors either in thin films (layered structures) or in particulate suspensions is a challenging issue that will be outlined promptly. 

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