Powder processing of thermoelectric materials-focusing on SiGe with new sintering technique

Big efforts have long been done to develop SiGe alloys known as a promising thermoelectric material for high temperature applications. Because of difficulty in manufacturing, which has resulted in less economical competitiveness, the practical application of the material has been almost limited to the power source for the space satellites. Reduction of manufacturing costs will be inevitable to conduct further industrial applications of the SiGe having high thermoelectric potentiality. Conventional hot-pressing, including a combination of hot-pressing with mechanical alloying, have contributed to enhancement of the thermoelectric performances. In these several years, Spark-Plasma-Sintering (SPS) or Plasma-Activated-Sintering (PAS) technique have been utilized for processing thermoelectric materials, in particular, SiGe alloys. One of the successful results will be co-sintering of p- and n-type material which can necessarily form a p-n junction to be used as a hot temperature end. This paper will report on the SPS technique we have applied to sinter SiGe alloys together with their properties