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Reactions under High Gas Pressure
    

Reactive Gas Pressure Synthesis

The development of a special equipment for synthesis and handling of samples under high-purity conditions and protective atmosphere is closely related to the general progress made in the area of solid state chemistry. From this point of view nitride-diazenides and hydrido-platinates represent fundamental examples of compounds which are available by reactive gas pressure methods. The parameter gas pressure is a crucial tool for selective syntheses by adjusting the redox-potential of the reaction gas by varying its pressure.

Figure 1. Schematic sketch of the high-pressure device for reactive gas pressure syntheses.

The device for reactive gas pressure syntheses includes high-pressure autoclaves made from Inconel, which are sealed with copper gaskets. The reaction pressure is measured and registered during the synthesis. High-pressures are obtained by using the following procedure: The high-pressure autoclave is cooled down with liquid nitrogen and the reaction gas (N2, H2, D2, Ar) or a gas mixture is condensed from gas bottles and/or medium reaction vessels, respectively, into the autoclave (all autoclaves are connected in series). This technique facilitates access to reaction pressures within the autoclave up to a desired value taking into account all necessary aspects of safety. The reaction volume of the autoclave is about 14 cm3. The maximum value of the reaction temperature strictly depends on the reaction pressure and should not exceed (pmax 6000 bar (T<925 K)/Tmax 1100 K (p<500 bar)).

Figure 2. Photograph of the high-pressure device for reactive gas pressure syntheses.

Using this method numerous nitride-diazenides and hydridometalates/hydrides were synthesized by starting from the elements.

Figure 3. Controlled formation of intermediate phases gained by adjusted gas pressure in the strontium-nitride-diazenide pressure series.


Contact

Dr. Gudrun Auffermann
Phone +49 (0) 351 4646-3201
Fax +49 (0) 351 4646-3002
aufferma[at]cpfs.mpg.de


References:

[1] W. Bronger, G. Auffermann, Chem. Mat., 10 (1998) 2723
[2] G. Auffermann, Yu. Prots, R. Kniep, Angew. Chem., 113 (2001) 545, Angew. Chem. Int. Ed., 40 (2001) 565
[3] Yu. Prots, G. Auffermann, M. Tovar, R. Kniep, Angew. Chem., 114 (2002) 2392; Angew. Chem. Int. Ed., 41 (2002) 2288
[4] G. Auffermann, R. Kniep, W. Bronger, Z. Anorg. Allg. Chem., 632 (2006) 565
[5] E. Horvath-Bordon, R. Riedel, A. Zerr, P. F. McMillan, G. Auffermann, Yu. Prots, W. Bronger, R. Kniep, P. Kroll, Chem.Soc. Rev., 35 (2006) 987

Last modified on January 28, 2010 Print version         Top
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