Microwave plasma synthesis of Si/Ge and Si/WSi2nanoparticles for thermoelectric applications

Nils Petermann, Tom Schneider, Julia Stötzel, Niklas Stein, Claudia Weise, Irenäus Wlokas, Gabi Schierning, Hartmut Wiggers
2015 Journal of Physics D: Applied Physics  
The utilization of microwave-based plasma systems enables a contamination-free synthesis of highly specific nanoparticles in the gas phase. A reactor setup allowing stable, long-term operation was developed with the support of computational fluid dynamics. This paper highlights the prospects of gas-phase plasma synthesis to produce specific materials for bulk thermoelectrics. Taking advantage of specific plasma reactor properties such as Coulomb repulsion in combination with gas temperatures
more » ... gas temperatures considerably higher than 1000 K, spherical and non-aggregated nanoparticles of multiple compositions are accessible. Different strategies towards various nanostructured composites and alloys are discussed. It is shown that, based on doped silicon/germanium alloys and composites, thermoelectric materials with zT values up to almost unity can be synthesized in one step. First experimental results concerning silicon/tungsten silicide thermoelectrics applying the nanoparticle-in-alloy idea are presented indicating that this concept might work. However, it is found that tungsten silicides show a surprising sinter activity more than 1000 K below their melting temperature.
doi:10.1088/0022-3727/48/31/314010 fatcat:xjrtodscy5gh7nv7qe5rgo3ruy