Influences of milling media on the fabricating process and thermoelectric properties of silicon germanium alloys

In this work, Si80Ge20P2 alloys were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). SiO2 and ZrO2 were taken as milling media respectively to investigate the effect of milling media on the fabricating process and the thermoelectric properties of SiGe alloys. The results show that, compared with the zirconia ball, though the agate one contains less kinetic energy, the solid solution of SiGe taken it as the milling media forms more quickly and at the same time has smaller average grain size through the whole milling time. The solid solution of Ge to Si crystal of samples under ZrO2 media remains stably around 98% and is much higher than that of specimens with agate as the media. In the sintering process, the previous application of ZrO2 easily causes the enrichment of elementary P and the loss of Si and leads to serious deviation from the original stoichiometric proportion of the compounds which is beneficial to the following machining and finally does harm to the thermoelectric properties of the Si80Ge20P2 alloys. (C) 2013 Elsevier B.V. All rights reserved.