Formation of the Te-Rich Phase in (Bi_(1-x)Sb_x)_2Te_3 Alloys Prepared by the MA-PDS Process

摘要

The structural evolution of the (Bi_(1-x)Sb_x)_2Te_3 thermoelectric alloys made by mechanical alloying and pulse discharge sintering was studied by DSC. It has been shown that, in addition to the (Bi, Sb)_2Te_3 hexagonal solid-solution phase, a Te-rich phase was developed at x = 0.0 ～ 0.5 and 0.75 ～ 1.0; whereas a Bi-rich phase was formed at x = 0.6 ～ 0.725. The effects of the Te- or Bi-rich phase on the type and density of the charge carriers as well as the electrical transport properties were discussed.