Zone leveling crystal growth of thermoelectric PbTe alloys with Sb _2Te_3 widmanst?tten precipitates

摘要

Unidirectional solidification of PbTe-rich alloys in the pseudobinary PbTe-Sb_2Te_3 system using the zone leveling technique enables the production of large regions of homogeneous solid solutions for the formation of precipitate nanocomposites as compared with Bridgman solidification. (PbTe)_(0.940)(Sb_2Te_3) _(0.060) and (PbTe)_(0.952)(Sb_2Te_3) _(0.048) alloys were successfully grown using (PbTe) _(0.4)(Sb_2Te_3)_(0.6) and (PbTe) _(0.461)(Sb_2Te_3)_(0.539) as seed alloys, respectively, with 1 mm h~(-1) withdrawal velocity. In the unidirectionally solidified regions of both alloys, Widmanst?tten precipitates are formed due to the decrease in solubility of Sb _2Te_3 in PbTe. To determine the compositions of the seed alloys for the zone leveling experiments, the solute distribution in solidification in the PbTe-richer part of the pseudobinary PbTe-Sb _2Te_3 system has been examined from the concentration profiles in the samples unidirectionally solidified by the Bridgman method.