| Thermoelectric properties of p-type polycrystalline (Bi_(1-x)Sb_x)₂Te₃ (0.75 ≤ x ≤ 0.85), fabricated by mechanical alloying and hot pressing, were investigated as a function of the Sb₂Te₃ content and the amount of excess Te addition. The effect of a reduction treatment in Hz atmosphere on thermoelectric properties of (Bi_(1-x)Sb_x)₂Te₃ was also studied. Among (Bi_(1-x)Sb_x)₂Te₃ fabricated by mechanical alloying. (Bi_(0.2)Sb_(0.8))₂Te₃ exhibited the highest figure-of-merit of 2.98×10³/K. When (Bi_(1-x)Sb_x)₂Te₃ powders were reduction-treated in H₂ atmosphere, the Seebeck coefficient and electrical resistivity decreased due to the removal of the oxide layer on the powder surface. With the reduction treatment, the figure-of-merits of (Bi_(0.25)Sb_(0.75))₂Te₃ (Bi_(0.2)Sb_(0.8))₂Te₃, (Bi_(0.15)Sb_(0.85))₂Te₃ were changed from 2.76×10^(-3)/K to 2.79×10^(-3)/K, from 2.98×10^(-3)/K to 2.80×10^-3/K, and from 2.78×10^(-3)/K to 1.81×10^(-3)/K, respectively. When 1.0 wt% excess Te-doped (Bi_(0.2)Sb_(0.8))₂Te₃ powders were reduction-treated, a Figure-of-merit of 3.33×10^(-3)/K was obtained. |
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