Effects of a reduction treatment and Te doping on thermoelectric properties of (Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ fabricated by mechanical alloying

(Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ (0.75/spl les/x/spl les/0.85) thermoelectric materials were fabricated by mechanical alloying and hot pressing at 550/spl deg/C for 30 minutes with and without reduction treatment of the mechanically alloyed powders. When the mechanically alloyed (Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ powders were hot-pressed without a reduction treatment, a maximum figure-of-merit of 2.92/spl times/10/sup -3//K at 300 K was obtained for x=0.8 composition. Although the electrical resistivity of the mechanically alloyed (Bi/sub 1-x/Sb/sub x/)/sub 2/Te/sub 3/ decreased with a reduction treatment of the powders, the figure-of-merit was lowered due to the substantial decrease of the Seebeck coefficient. With addition of 1 wt% excess Te, the figure-of-merit of the reduction-treated (Bi/sub 0.2/Sb/sub 0.8/)/sub 2/Te/sub 3/ could be improved to be 3.33/spl times/10/sup -3//K.