Calcium chemical vapor deposition

Chemical Vapor Deposition of CaO and Calcium Vanadate Films... 

Calcium- and strontium fluoride [3] each serve as components in fluoride glasses and have been used as insulators on GaAs. Photoassisted CVD utilizing calcium hexafluoroacetylacetonate (Ca(hfac)2 hfac 3) as a precursor molecule at a substrate temperature of 350°C yields polycrystalline layers of Cap2 [3]. Another source which has been used for the chemical vapor deposition of Cap2 is calcium trifluoroacetylace-tonate (Ca(tfac)2 tfac 3) [3]. 

Preparation of uranium metal. As discussed previously, some nuclear power plant reactors such as the UNGG type have required in the past a nonenriched uranium metal as nuclear fuel. Hence, such reactors were the major consumer of pure uranium metal. Uranium metal can be prepared using several reduction processes. First, it can be obtained by direct reduction of uranium halides (e.g., uranium tetrafluoride) by molten alkali metals (e.g., Na, K) or alkali-earth metals (e.g.. Mg, Ca). For instance, in the Ames process, uranium tetrafluoride, UF, is directly reduced by molten calcium or magnesium at yoO C in a steel bomb. Another process consists in reducing uranium oxides with calcium, aluminum (i.e., thermite or aluminothermic process), or carbon. Third, the pure metal can also be recovered by molten-salt electrolysis of a fused bath made of a molten mixture of CaCl and NaCl, with a solute of KUFj or UF. However, like hafnium or zirconium, high-purity uranium can be prepared according to the Van Arkel-deBoer process, i.e., by the hot-wire process, which consists of thermal decomposition of uranium halides on a hot tungsten filament (similar in that way to chemical vapor deposition, CVD). 

Powder pressing generally forms boron nitride substrates. Various sihca and/or calcium compounds may be added to lower the processing temperature and improve machinabihty. Diamond substrates are typically formed by chemical vapor deposition (CVD). Composite substrates, such as AlSiC, are fabricated by creating a spongy structure of SiC, and forcing molten aluminum into the crevices. 

Jash, R and Trenary, M. Synthesis of crystaUine boron nanoribbons and calcium hexaboride nanowires by low pressure chemical vapor deposition. Journal of Physics Cortference Series, 21MI9,176,012011(1-11). 

Synthetic routes derived from molecular and non-molecular precursors have expedited the development of technologically important 2- and 3- dimensional materials. Such approaches have often proved superior to conventional ceramic techniques in that high purity bulk samples or thin films can be prepared at lower temperatures much more rapidly. Predominant among the precursor methods are those based on decomposition reactions. These either involve gaseous species, such as those used in chemical vapor deposition (CVD), or solids. Examples include the pyrolysis of the gas-phase precursor [(CH3)2A1(NH2)]3 to produce aluminum nitride (i) and the thermal decomposition of solid state carbonate precursors of calcium and manganese (Cai j,Mn C03, 0 < x < 1) to produce several of the known ternary compounds in the Ca-Mn-O system (2). Single-displacement reactions are also common as precursor methods. These approaches usually involve gas-phase reactions and are also used in CVD techniques. Examples here include the formation oi... 

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