Tantalum sulfide TaS

S2Ta N0C(,H 3, Hexanamide. compd. with tantalum sulfide (Ta 2). [34294-11-61,30 164 S2Ta NOC gH37. Octadecanamide. 

Tantalum sulfide (TaS,), compd. with pyridine (2 1), 30 161 [34200-66-3), Octadecanamide, compd. with tantalium sulfide (TaS2). 30 164 [34200-70-9], Benzenecarbothioamide, compd. with tantalum sulfide (TaS ). 30 164... 

The double-sealed reaction tube was placed in a SiC furnace and heated at 1007h to 400° then ramped at 10°/h to 6(X)°. The slow increase in temperature between 4(X) and 600° provides time for the sulfur to react to form tantalum sulfides and thus prevents the buildup of an excessive sulfur pressure in the reaction tube. At 600° the vapor pressure of sulfur over liquid sulfur is approximately 10 atmospheres. Larger scale reactions may require the reaction to be held at 6(X)° to provide additional time for the reaction of Ta and S. From 600° the reaction was heated at 50°/h to 1180°. After 5 days the furnace was cooled to 850° and the silica reaction vessel was carefully removed (note safety precautions above) and cooled on a firebrick. 

Ta 2 NjCHj, Guanidine, compd. with tantalum sulfide (TaS2), [53327-76-7], 30 164... 

Differences in the cohesive energy between Nb and Ta give rise to the formation of a bundle of (Nb, Ta)-rich sulfides without counterparts in the corresponding binary M-S systems. The phase richest in metal of this class has been identified as NbxTa7 xS2. (Nb, Ta)7S2 is an excellent example of a mixed niobium-tantalum-rich sulfide without counterpart in the adjoining binary systems. Its structure differs... 

Because the sulfides of metals have a lower heat of formation than the oxides, some difficult-to-obtain metals can be made from their lulfides with aluminum. This process has been described by Gardner > for niobium (columbium) and tantalum from their disulfides (NbS and TaSj), whereby the relatively volatile by-product Al S, distills off above 1550°C. It is an interesting coincidence that the production of the same two metals by reduction of the pentoxides NbfOs and Ta s with silicon can be performed under formation of silicon (II) oxide (SiO), which volatilizes in vacuum. 

The key property required of the inorganic species is ability to build up (polymerize) around the template molecules into a stable framework. As is already evident in this article, the most commonly used inorganic species are silicate ions, which yield a silica framework. The silica can be doped with a wide variety of other elements (heteroatoms), which are able to occupy positions within the framework. For example, addition of an aluminium source to the synthesis gel provides aluminosilicate ions and ultimately an aluminosilicate mesoporous molecular sieve. Other nonsilica metal oxides can also be used to construct stable mesoporous materials. These include alumina, zirconia, and titania. Metal oxide mesophases, of varying stability, have also been obtained from metals such as antimony (Sb), iron (Fe), zinc (Zn), lead (Pb), tungsten (W), molybdenum (M), niobium (Nb), tantalum (Ta), and manganese (Mn). The thermal stability, after template removal, and structural ordering of these mesostructured metal oxides, is far lower, however, than that of mesoporous silica. Other compositions that are possible include mesostructured metal sulfides (though these are unstable to template removal) and mesoporous metals (e.g., platinum, Pt). 

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