Comparison of the thermoelectric properties of (Bi,Sb)/sub 2/Te/sub 3/ alloys prepared by powder metallurgy with single crystals

Thermoelectric properties of the polycrystalline (Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ (0/spl les/x/spl les/1) alloys, prepared by various powder metallurgy such as mechanical alloying and melting/grinding, were measured and compared with the characteristics of single crystals. Contrary to the p-type behavior of the single crystals in all compositions of 0/spl les/x/spl les/1, a p-n transition occurred at about 0.67 mol% Sb/sub 2/Te/sub 3/ for the alloys prepared by powder metallurgy. Among the p-type (Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ (x/spl ges/0.7) processed by powder metallurgy, (Bi/sub 0.2/Sb/sub 0.8/)/sub 2/Te/sub 3/ exhibited the highest figure-of-merit of 3.05/spl times/10/sup -3//K. Thermoelectric properties of the hot-pressed (Bi/sub 0.2/Sb/sub 0.8/)/sub 2/Te/sub 3/ with addition of BN powders as scattering centers were also investigated.