Volatility at low temperature

Sufficient volatility at low temperature so that it can be easily transported to the reaction zone without condensing in the lines. 

A particularly interesting case is that of the platinum metal group which, in addition to platinum (Pt), comprises ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), and palladium (Pd). These carbonyl halides are usually the most practical precursors for metal deposition because of their high volatility at low temperature. Indeed two of them, palladium and platinum, do not form carbonyls but only carbonyl halides. So does gold. 

Another test method for the determination of mercury in coal (ASTM D-6414) involves (method A) solubilizing of the mercury in the sample by heating the sample at a specified temperature in a mixture of nitric and hydrochloric acids. The acid solutions produced are transferred into a vessel in which the mercury is reduced to elemental mercury. The mercury vapor is determined by flameless cold-vapor atomic absorption spectroscopy. An alternative method (method B) involved solubilization of the mercury by heating the sample in a mixture of nitric acid and sulfuric acid with vanadium pentoxide. The acid solution is then transferred into a vessel in which the mercury is reduced to elemental mercury. The mercury content is determined by flameless cold-vapor atomic absorption spectroscopy. However, mercury and mercury salts can be volatilized at low temperatures, and precautions against inadvertent mercury loss should be taken when using this method. 

The chemical reactions used in CVD are pyrolysis, hydrolysis, disproportionation, reduction, oxidation, carburization, and nitridization [16]. The selection of the precursors is regulated by general features that can be summarized as follows [17] stability at room temperature, enough volatility at low temperature, high purity, ability to react plainly on or with the support, and ability to react without the production of side or parasitic reactions. 

Table XI gives the limits of possible fluctuations of the composition of the fluid in equilibrium with graphite and with typical iron mineral associations in the conditions of the main facies of metamorphism. For T = 827°C, where strict limits cannot be set on the composition of the fluid in equilibrium with just the one iron mineral (fayalite), two extreme variants are arbitrarily taken in one HjO predominates in the fluid (C02/[H20 + CO2] = 10), and in the other CO2 (H20/[H20 + CO2] = 10). From the table it is seen that, at all T and P, water and carbon dioxide predominate in the fluid the content of other volatiles at low temperatures is negligible, and at high temperatures...

The polysiloxane network is formed during part fabrication. In injection molding, the acetylenic alcohol, which acts as a fugitive inhibitor of the vinyl-addition reaction, is volatilized at low temperature as the pellets enter the feed throat. The platinum complex is activated at the process temperature of the urethane (170-185 °C). The vinyl-addition reaction is initiated by the melt state, and the parts generated demonstrate mechanical properties consistent with the formation of a silicone IPN. The fabricated parts are translucent. The physical properties of this formulation (PTUE 205) are given in Table 1. 

The alkyl boric acids, RB(OH), ff s jb prepared by the action of magnesium alkyl halides on boric iJ llilhey are all solids, and the lower members of. the series are volatile at low temperatures. ... 

Cr, Cu, Hg, Ni, Pb, Zn. These heavy metals are mainly concentrated in the residual char with the exception of As, Hg and Cd, which are volatile at low temperatures. A large fraction of these last three metals are recovered in the tars. The same phenomenon... 

With regard to the heavy metals contents of the pyrolysis products, we can say that the heavy metals mainly concentrate in the charcoal except mercury, arsenic and cadmium which are volatile at low temperatures. Significant quantities of diese three heavy metals are found in the pyrolytic oil. 

In some cases such as in the analysis of ZrC>2, use is made of ammonium salts. This has the advantage that the melting procedure can be performed in quartz crucibles limiting the risk of contamination, that the salts are relatively pure as they can be prepared from pure chemicals (NH3 gas and CIHSO3, e.g. see Ref. [312]), and that the excess can be volatilized at low temperatures which makes the risk of analyte losses through volatilization low. For example, with NH4HSO4, the melting procedure can be performed at 400 °C and the excess of flux volatilized at below 500 °C. 

Sulfide minerals show oxidation and decomposition by releasing SO2 accompanied by a mass loss during heating. The decomposition and oxidation reactions take place at temperatures from 300 to 800 °C. Sulfide of many elements is transformed into complex oxides, some of which are volatilized at low temperature whereas others melt at high temperature. Some Sulfide is poly-morphically transformed before oxidation and decomposition. 

Operating nuclear reactors have within their fuel pins a large amount of highly radioactive and radiotoxic fission products, some of which are volatile at low temperatures. These include in particular iodine-131, and cesium-137. There are also non-volatile but radiotoxic alpha-emitters such as plutonium-239. Hence the third requirement is that there must be robust containment of all the fission products under all foreseeable design-basis conditions. 

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