Pyrolysis metal deposition

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). 

The beryllium halides are stable compounds and consequently their reducti on by hydrogen i s not a practical method of obtaining the metal. Pi Good beryllium deposits are obtained by the pyrolysis of the alkyls as follows ... 

Porous aluminum oxide can be used as a template for the production of nanowires and nanotubes. For example, metals can be deposited on the pore walls by the following procedures deposition from the gas phase, precipitation from solution by electrochemical reduction or with chemical reducing agents, or by pyrolysis of substances that have previously been introduced into the pores. Wires are obtained when the pore diameters are 25 nm, and tubes from larger pores the walls of the tubes can be as thin as 3 nm. For example, nanowires and nanotubes of nickel, cobalt, copper or silver can be made by electrochemical deposition. Finally, the aluminum oxide template can be removed by dissolution with a base. 

Silver(I) /3-diketonate derivatives have received significant attention due to the ease with which they can be converted to the elemental metal by thermal decomposition techniques such as metal organic chemical vapor deposition (MOCVD).59 The larger cationic radius of silver(I) with respect to copper(I) has caused problems in achieving both good volatility and adequate stability of silver(I) complexes for the use in CVD apparatus. These problems have been overcome with the new techniques such as super critical fluid transport CVD (SFTCVD), aerosol-assisted CVD (AACVD), and spray pyrolysis, where the requirements for volatile precursors are less stringent. 

Films at NASA GRC were deposited using homemade spray or aerosol-assisted chemical vapor deposition (AACVD) reactors to exploit the lower deposition temperature enabled by the simpler decomposition chemistry for the SSPs.6 9 AACVD is a simple and inexpensive process that offers the advantage of a uniform, large-area deposition, just like metal organic CVD (MOCVD), while also offering the low-temperature solution reservoir typical of spray pyrolysis methods. 

Xie Y, Neagu R, Hsu CS, Zhang X, and Deces-Petit C. Spray pyrolysis deposition of electrolyte and anode for metal-supported solid oxide fuel cell. J. Electrochem. Soc. 2008 155 B407-B410. 

In a review by Gonsalves el al. (2000), techniques for the fabrication of nano-structured materials are outlined. Synthesis from corresponding organo-metal precursors of nano-structured metals (Fe, Co, Ni) and alloys (Fe-Co, Pt-Pd, and special steels) are discussed and various methods considered such as thermal decomposition, ultrasonic irradiation, chemical vapour deposition, laser pyrolysis and reduction. 

Membranes with extremely small pores ( < 2.5 nm diameter) can be made by pyrolysis of polymeric precursors or by modification methods listed above. Molecular sieve carbon or silica membranes with pore diameters of 1 nm have been made by controlled pyrolysis of certain thermoset polymers (e.g. Koresh, Jacob and Soffer 1983) or silicone rubbers (Lee and Khang 1986), respectively. There is, however, very little information in the published literature. Molecular sieve dimensions can also be obtained by modifying the pore system of an already formed membrane structure. It has been claimed that zeolitic membranes can be prepared by reaction of alumina membranes with silica and alkali followed by hydrothermal treatment (Suzuki 1987). Very small pores are also obtained by hydrolysis of organometallic silicium compounds in alumina membranes followed by heat treatment (Uhlhom, Keizer and Burggraaf 1989). Finally, oxides or metals can be precipitated or adsorbed from solutions or by gas phase deposition within the pores of an already formed membrane to modify the chemical nature of the membrane or to decrease the effective pore size. In the last case a high concentration of the precipitated material in the pore system is necessary. The above-mentioned methods have been reported very recently (1987-1989) and the results are not yet substantiated very well. 

This method is based on pyrolysis of a metal chalcogenide-containing precursor. Heating CD hydroxide films to form oxides is a simple example and is common in the deposition of some oxides. This will be treated in Chapter 7, which... 

A. Pyrolysis and Chemical Vapor Deposition Metal Silicides. 107... 

Spray pyrolysis An appropriate metal salt is sprayed from an atomizer onto a hot substrate where decomposition occurs yielding the metal oxide. There are advantages to be gained by electrically charging the droplets using an electrostatic atomizer Deposition rates are quite low, typically in the range 1-10 /unh-1. 

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