Metal oxides, inorganic films

There is much current interest in volatile compounds of some of the metallic elements which may be useful for CVD of thin films of electronic or structural materials.1 Among the presently utilized precursors for metal oxide-containing films, the /i-diketonate family has been employed by numerous researchers.2 A previous volume of Inorganic Synthesis described the general... 

Figure 6.1. Wet processes for the preparation of ultrathin metal oxide thin films, (a) 2D sol-gel process at the air/water interface [3], (b) repeated adsorption and UV-ozone oxidation of alkylsiloxane monolayer (R = C18H37) [5], and (c) two-step adsorption cycle of alternate electrostatic adsorption of linear polymers and inorganic sheets [7] ((b) is with permission of American Chemical Society and (c) is with permission of...

Metal or metal oxides may be added to perform specific functions. Brass chips and copper powder are frequently used in heavy-duty organics where these metaUics act as scavengers to break up undesirable surface films. Zinc chips used in Class A organics contribute significantly to recovery of normal performance following fade. Aluminum is also used. Most of these inorganic materials tend to detract from antinoise properties and mating surface compatibihty. 

A thin film (typically 50-200 nm) is grown from solution to serve as a hybrid inorganic/organic gradient between the metal (oxide) surface and the organic primer or adhesive. XPS indicates that the surface is silane-rich and the... 

Abstract In the last decade, the sonoelectrochemical synthesis of inorganic materials has experienced an important development motivated by the emerging interest in the nanostructures production. However, other traditional sonoelectrochemical synthesis such as gas production, metal deposits and metallic oxide films have also been improved with the simultaneous application of both electric and ultrasound fields. In this chapter, a summary of the fundamental basis, experimental set-up and different applications found in literature are reported, giving the reader a general approach to this branch of Applied Sonoelectrochemistry. 

Another way to complete condensation of an inorganic matrix is a treatment of the deposited films at different humidity in combination with slightly elevated temperatures. This approach, called delayed humidity treatment (DHT), enables controlled mesoorganization and condensation of the metal oxides (e.g., Sn02) with a low condensation rate.53,54 The thermal stability of such mesostructures is, however, low. So, in most cases, just semicrystalline metal oxide films can be obtained. 

In 1988, Tanaka et al. first reported the use of ultrafine metal powder in protein analysis. Since then, many inorganic materials, including graphite particles, fine metal or metal oxide powder, silver thin-film substrates or particles,and silica gel, have been used in the MALDI-TOF analysis of low-mass molecules. 

Inorganics can also be synthesized and used as templates. Thus, controlled siloxane networks were formed when dispersions of alkoxysilanes (such as (MeO)3SiMe) are mixed with the suitable template matrixes. Ultrafine particles of metal oxides can be used as starting materials for the formation of metal oxide films. For instance, a mixture of a double-chained ammonium amphiphile and an aqueous solution of aluminum oxide particles (diameter about 10 100 nm) gives a multilayered aluminum oxide film when calcinated at over 300°C. 

A minimum chromium concentration of approximately 11% is typical for stainless steel. As more chromium is added, corrosion resistance improves. Concentrations of chromium >20% are found in some alloys. Chromium addition leads to the formation of a tight-forming oxide film on the surface of the metal. This stable film is self-healing, which means that the film will reform if scratched or broken. This oxide is quite resistant to attack by acids, bases, organic compounds, and inorganic salts. 

In the polymeric sol-gel process, partial hydrolysis of a metal alkoxide dissolved in alcohol is accomplished by adding the minimum of water to the solution. The active hydroxyl groups on the alkoxides then react to form an inorganic polymer molecule that can then be coated onto the ceramic support. On drying and sintering, the metal oxide film forms. Chemically the polymeric sol-gel process can be represented as ... 

Different methods have been used to deposit microporous thin films, including solgel, pyrolysis, and deposition techniques [20], Porous inorganic membranes are made of alumina, silica, carbon, zeolites, and other materials [8], They are generally prepared by the slip coating method, the ceramic technique, or the solgel method (Section 3.7). In addition, dense membranes are prepared with metals, oxides, and other materials (Chapter 2). 

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