Plasma metal reaction

Two methods of producing nanostructured MgH were already briefly mentioned in Sect. 2.1.3.3 and 2.1.5. Shao et al. [44] used the hydrogen plasma-metal reaction to obtain ultrafine magnesium with an average size of about 300 nm. The activation of... 

H. Shao, Y. Wang, H. Xu, X. Li, Hydrogen storage properties of magnesium ultrafine particles prepared by hydrogen plasma-metal reaction, Mater Sci. Eng. B 110 (2004) 221-226. 

Shao et al. [25] prepared Mg Ni from magnesium and nickel nanoparticles produced by hydrogen plasma-metal reaction. Two preparation methods were developed to obtain the compound. One is heating the nanoparticles under 0.10 MPa argon pressure at 430°C and the other is under 3.00 MPa hydrogen pressure at 280°C. No hydrogen storage properties of this material were assessed. 

Fig. 8.1.2 Schematic model of nitriding zone of iron vapor and/or condensed iron particles in reactive plasma-metal reaction. (From Ref. 17, p. 412. with kind permission from The Japan Institute of Metals.)...

In order to improve the kinetics of the Li-N-H system, Xie et al. [96] prepared Li2NH hollow nanospheres by plasma metal reaction based on the Kirkendall effect. The special nanostructure showed significantly improved hydrogen storage kinetics compared to that of the Li2NH micrometer particles. The absorption temperature decreased markedly, and the absorption rate was enhanced dramatically because... 

In addition, the hydrogen plasma-metal reaction (HPMR) method was applied to synthesize rare earth oxide nanoparticles [13], which has been used to prepare better metallic ultrafine particles industrially at low cost. Pure Sm and Nd oxide nanoparticles were prepared through the HPMR method followed by oxidation treatment. The first step is to fabricate hydride nanoparticles the second is to oxidize them at room or elevated temperatures. Cubic neodymium and samarium oxides were synthesized with their average sizes of 20 and 40 nm, respectively. 

Plasma electrochemical reactions have been studied by chemists for a surprisingly long time, with the first report on cathodic metal deposition at the free surface of a liquid electrolyte with free electrons from a plasma dating back to 1887 [1], long before the plasma state had been named by Langmuir in 1928 [2], A short survey of past work with more conventional liquid electrolytes is also included in this chapter. 

The major IH emphasis for dry etchers has been on potential exposures to maintenance personnel working on the reaction chambers, pumps, and other associated equipment that may contain reaction product residues. The complexity of plasma metal etchers and the difficulty in characterizing the odors associated with their maintenance has made them the subject of many investigations and a few published papers. 

The reaction products formed in plasma metal etchers are a complex mixture of chlorinated and fluorinated compounds. The maintenance of metal etchers often involves short duration operations that generate strong odors. Hexachloroethane was found to be the major cause of odor in one type of aluminum etcher.h l In another, cyanogen chloride was the main problem exposure levels were 11 times the 0.3 ppm TLV .[20] In still other types of etchers, hydrogen chloride is associated with the odor (maximum exposure measured was 68 ppm odor threshold for HCl is less than 5 ppm). The paper by Mueller and Kunesh is a good source of additional information on the subject.I l... 

Germanium difluoride can be prepared by reduction (2,4) of GeF by metallic germanium, by reaction (1) of stoichiometric amounts of Ge and HF in a sealed vessel at 225°C, by Ge powder and HgF2 (5), and by GeS and PbF2 (6). Gep2 has been used in plasma chemical vapor deposition of amorphous film (see Plasma TECHNOLOGY Thin films) (7). 

Reactions of boron ttihalides that are of commercial importance are those of BCl, and to a lesser extent BBr, with gases in chemical vapor deposition (CVD). CVD of boron by reduction, of boron nitride using NH, and of boron carbide using CH on transition metals and alloys are all technically important processes (34—38). The CVD process is normally supported by heating or by plasma formed by an arc or discharge (39,40). 

By tire coiTect choice of the metal oxide/carbon ratio in the ingoing burden for the furnace, the alloy which is produced can have a controlled content of carbon, which does not lead to the separation of solid carbides during the reduction reaction. The combination of the carbon electrode, tire gaseous oxides and the foamed slag probably causes tire formation of a plasma region between the electrode aird the slag, and this is responsible for the reduction of elecU ical and audible noise which is found in this operation, in comparison with tire arc melting of scrap iron which is extremely noisy, and which injects unwanted electrical noise into the local electrical distribution network. 

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