Preparation and characterization of segmented-type thermoelectric branches of Bi/sub 2/Te/sub 3//PbTe

Thermoelectric materials, metal/semiconductor joints and segmented-type thermocouple branches were prepared by plasma-activated sintering (PAS) using powdered source materials of Bi/sub 2/Te/sub 3/, 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 Bi/sub 2/Te/sub 3/ 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 Bi/sub 2/T/sub 3//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 Bi/sub 2/Te/sub 3//PbTe joints, respectively, to keep low resistance. The thermoelectric branches were Ni/Bi/sub 2/(Te,Se)/sub 3/Ni/PbTe/Ni for n-type and Ni/(Bi,Sb)/sub 2/Te/sub 3//Ni/SnTe/PbTe/SnTe/Ni for p-type.