Getters properties

Barium is prepared commercially by the thermal reduction of barium oxide with aluminum. Barium metal is highly reactive, a property which accounts for its principal uses as a getter for removing residual gases from vacuum systems and as a deoxidiser for steel and other metals. 

Pure barium metal has few commercial uses because of it reactivity with air and water. Nevertheless, this property makes it useful as a getter or scavenger to remove the last traces of gas from vacuum tubes. Barium metal is used to form alloys with other metals. One alloy is used to make sparkplugs that easily emit electrons when heated, thus improving the efficiency of internal combustion engines. 

The most important applications of zirconium involve its alloys, Zircaloy. The aUoy offers excellent mechanical and heat-transfer properties and great resistance to corrosion and chemical attack. This, in conjunction with the fact that zirconium has a low neutron absorption cross section, makes this ahoy a suitable choice as a construction material for thermal nuclear reactors and nuclear power plants. Other uses are as an ingredient of explosive mixtures, as getter in vacuum tubes, and in making flash bulb, flash powder (historical), and lamp filaments, in rayon spinnerets, and in surgical appliances. 

Chemical Properties. In the uses of chemical properties the high affinity of the rare earth metals for os gen is primarily involved. This leads to their application as flints, vdierein their highly exothermic reaction with os gen in air is used. On the same properties rests their application as getter metals, vherein residual os gen, as for exanple in amplifier tubes, is bound up. 

EJB, etc.) to do the actual work, because the action class is a Web component. It takes HTTP Request as an argument into its execute() method. Coding business logic in the action class makes it less reusable and difficult to test. Action Form is a Java Bean that holds user input from the HTML form. It has the setter methods that Struts uses to set its properties from the HTTP Request object. It also has getter methods that the action class uses to access these properties. Figure 11.3 illustrates a hypothetical compound registration transaction using the Struts framework. 

Because hafnium has a high absorption cross-section for thermal neutrons (almost 600 times that of zirconium), has excellent mechanical properties, and is extremely corrosion resistant, it is used to make the control rods of nuclear reactors. It is also applied in vacuum lines as a getter —a material that combines with and removes trace gases from vacuum tubes. Hafnium has been used as an alloying agent for iron, titanium, niobium, and other metals. Finely divided hafnium is pyrophoric and can ignite spontaneously in air. 

The GD plasma environment is an interesting vessel to study gas-phase chemical properties. The gettering qualities of carbon, silver, tantalum, titanium, and tungsten were compared by Mei and Harrison [40] on the basis of the atomic ion fraction of all of the observed lanthanum species R = La+/(La+ + LaO+) X... 

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