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Spark plasma synthesis (SPS)

Contact:  Igor Veremchuk


With increasing demand on new intermetallic compounds and materials on their basis new preparation techniques were developed in recent years. Spark plasma sintering (SPS) was previously implemented as an effective compaction technique. In this procedure a series of 3ms dc current pulses with the strength up to 1500 A and low voltage of 25 V directly pass the powdered sample and the pressing tool. This yields in a high-rate heating, whereby the main amount of heat is generated in the sample on the contacts between the powder particles, and a remarkable materials transport (diffusion) on the same places. There are a number of proposed mechanisms to account for the enhanced sintering behaviors, which are still under discussion.

MPI CPfS was first institute in Germany installed an SPS setup. Within the Dresden SPS center we cooperate with the Fraunhofer IFAM and IKTS institutes. Currently, there are 5 SPS units of different scale-operating in this centre.

We are using the mass transport and dc current for performing chemical reactions, especially in protective atmosphere. Several works were done on short time synthesis from mixture of elemental powders and compacting of the known and new phases as bulk materials by SPS technique: CoSb3, LaFe4Sb12, Ti5Si3, TiB2.

Firstly MgH2 was used as a precursor for SPS fabrication of Mg-based materials (MgB2 and Mg2Si). Mg2Si is one promising thermoelectric material at now. SPS process provided the simple method for producing of this material in large amounts and necessary shapes at ones.

Unique results were obtained during the SPS treatment of Zintl phase Na4Si4. Mm-sized single crystals of clathrate-II compound Na24Si136 were synthesized. The reported process is a solid state electrochemical variant of the redox reaction:

34 Si4 4– – 112 e → Si136 24– (anode)
112 Na+ + 112 e → 112 Na0 (cathode).

Last modified on January 27, 2011 Print version         Top
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