Zone Leveling Crystal Growth of Thermoelectric PbTe Alloys with Sb2Te3 Widmanstatten Precipitates

Unidirectional solidification of PbTe-rich alloys in the pseudobinary PbTe-Sb2Te3 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)(Sb2Te3)(0.060) and (PbTe)(0.952)(Sb2Te3)(0.048) alloys were successfully grown using (PbTe)(0.4)(Sb2Te3)(0.6) and (PbTe)(0.461)(Sb2Te3)(0.539) as seed alloys, respectively, with 1 mm h(-1) withdrawal velocity. In the unidirectionally solidified regions of both alloys, Widmanstatten precipitates are formed due to the decrease in solubility of Sb2Te3 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-Sb2Te3 system has been examined from the concentration profiles in the samples unidirectionally solidified by the Bridgman method.