Preparation and characterization of segmented-type thermoelectric branches of Bi2Te3/PbTe

Thermoelectric materials, metal/semiconductor joints and segmented-type thermocouple branches were prepared by plasma-activated sintering (PAS) using powdered source materials of Bi₂Te₃, PbTe and metals (Cu, Fe and Ni). The sintering was carried out in vacuum under a axial pressure of 45 MPa by pulse current heating followed by DC current heating, where temperature was differently controlled for sintering of Bi₂Te₃ and PbTe. The sintered materials were characterized by measuring the thermoelectric properties. The electron probe microanalyses indicated that no serious diffusion occurred at the joint interfaces of Fe/PbTe and Bi₂T₃/PbTe where an abrupt change of the potential voltage was observed in their p-type joints. Therefore SnTe and Ni layers were inserted in the Fe/p-PbTe and Bi₂Te₃ /PbTe joints, respectively, to keep low resistance. The thermoelectric branches were Ni/Bi₂(Te,Se)₃Ni/PbTe/Ni for n-type and Ni/(Bi,Sb) ₂Te₃/Ni/SnTe/PbTe/SnTe/Ni for p-type