Synthesis and Thermoelectric Properties of Some Materials with the PbBi4Te7 Crystal Structure

Polycrystalline samples of some compounds with the PbBi 4 Te 7 crystal structure have been synthesized and characterized by x-ray and microprobe analysis. Seebeck coefficient, electrical resistivity, and thermal conductivity measurements were also performed in the 300-650K temperature range. Their thermoelectric properties vary widely from semiconducting to semimetallic with both n- and p-type conduction and are anisotropic. All samples possess thermal conductivity values comparable or lower to those obtained for Bi 2 Te 3 -based alloys. The estimated lattice thermal conductivity values range from 4 to 6 mW/cmK at 350K. The best ZT value obtained was 0.55 at 400K for the SnBi 2.5 Sb 1.5 Te 7 composition.