Precursor high vapor pressure precursors

The best results were obtained with compound 21 that exhibited high vapor pressure and low decomposition temperature (<523 K). Various CVD conditions were applied and gave in all cases shiny, dark-brown deposits.43 XRD and XPS analyses of the deposits indicated the presence of a vanadium carbonitride phase with little contamination from oxygen and free carbon. The films were less adherent on steel substrates than on silicon ones. The steel substrates seemed to suffer corrosion due to the presence of Cl-containing species. We had noticed the same feature in the case of Cl-containing precursors to vanadium carbide. Therefore, in order to increase the volatility of compound 23 and to reduce the Cl content of the molecule, we prepared compounds 24 and 25. Unfortunately, the yields obtained in their syntheses were much too low to permit TG and CVD experiments. 

Uses Inexpensive Precursors Soluble precursors are used instead of expensive, high vapor pressure organometallics. 

Mixed metal Fe-Co alloys of variable composition have been prepared by the sonication of controlled stoichiometries of Fe(CO)s and Co(CO)3(NO). These compounds were chosen as precursors because of their solubility and high vapor pressure. Similar results have been obtained in a mixed-phase reaction by the sonication of Fe(CO)s and Co2(CO)8, both in decane and using Fe(CO)s as the sonication medium.The resulting mixed metal alloys were... 

Deposition of nanoparticles from vapor phase, as opposed to wet impregnation methods, does not alter the porous matrix and ensures that the guest phase will be distributed throughout the matrix, thanks to its open porous texture. The general applicability of this approach is limited by the availability of precursors with a sufficiently high vapor pressure to give rise to volatile by-products. 

It requires chemical precursors (the starter materials) with high vapor pressure which are often hazardous and toxic. 

Uses liquid or gaseous precursors wiiri high vapor pressure Uses precursors with low vapor pressure. 

The preparation of the precursor solution begins with the dissolution of silicon alkoxide or its derivatives in an organic solvent like hexane that meets the conditions (1) immiscible with water, (2) lower density than water, and (3) relatively high vapor pressure. Among commercially available silicon alkoxides and their derivatives, ethyl silicate 40 (E-40), partially hydrolyzed tetraelhoxysilane (TEOS) comprising the 5-membered oUgomers, turned... 

Mass Spectral Analysis of KAS Precursor. Fast atom bombardment (FAB) is the only technique that can be used for salts like the KAS precursor. FiAB requires that the sample be dispersed in a non-interactive matrix for analysis. Unfortunately, all three typical matrix materials, viz. TEA, p-nitrobenzylalcohol (NBA) and glycerol, interact/react with the sample. This problem was encountered during analysis of the spinel precursor (72). NBA was found to interact least with the spinel precursor and was used as the matrix in those studies (72). On this basis, an NBA matrix was used with the KAS precursor. EG can also be used as matrix but its high vapor pressure compared to other matrix materials, leads to much lower intensities for ion fragments. Results of FAB analyses done in both EG and NBA are shown in Table II. At the outset, nominal mass analysis by positive ion FAB were in accord with expectations. The molecular ion peak expected from the proposed precursor structure was seen, along with peaks resulting from interaction with the NBA matrix (Table II). 

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