Chemical vapor transport transporting agents

FeS2 crystals doped with Co were synthesized using a chemical vapor transport with FeBr3 as a transport agent [2006Leh]. Co concentration was 450-3700 ppm. 

Chemical vapor transport consists of two basic steps. The crystalline or semicrystalline powder of the MX2 compound is first prepared by heating a stoichiometric ratio of the elements in an evacuated silica tube in the first step. In the second step, the MX2 powder, together with a gaseous transporting agent... 

Chemical Vapor Deposition. In chemical vapor deposition (CVD), often referred to as vapor transport, the desired constituent(s) to be deposited are ia the form of a compound existing as a vapor at an appropriate temperature. This vapor decomposes with or without a reducing or oxidizing agent at the substrate— vapor interface for film growth. CVD has been used successfully for preparing garnet and ortho ferrite films (24,25). Laser-assisted CVD is also practiced. 

A follow-up study demonstrated that Qi phases further enhance the performance of LLC-BR composite membranes in both water transport and harmful chemical vapor rejection [170]. A cross-linkable, gemini phospho-nium amphiphile (Fig. 23) was blended with BR and cross-linked to form films exhibiting a Qi-phase nanostructure. Materials with a Qi-phase showed 300 times greater water vapor permeability and 500 times greater permeability selectivity for water/CEES than pure cross-linked BR. Furthermore, these Qi-phase composite films were far superior to their Hu and L analogues in both water vapor permeability and water/CEES transport selectivity. Further studies were planned to process thinner films as well as test their rejection properties against other types of chemical agents. 

Mercury is uniquely determined by the reduction of inorganic mercury compounds (Hg and Hg ) to the elemental state (Hg°) using a reducing agent, followed by the transport of the elemental Hg vapor to the plasma in the Ar carrier stream. A unique physical property of elemental Hg is its high vapor pressure at room temperature. The chemical stability of elemental Hg in the vapor form provides for an operationally simple apparatus and vapor transport system. 

Chemical Reactivity - Reactivity with Water No reaction, but water, provides heat to vaporize liquid cyanogen Reactivity with Common Materials No reaction Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

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