Thermoelectric properties of the p-type Bi2Te3-Sb2Te3-Sb2Se3 alloys fabricated by mechanical alloying and hot pressing

The p-type (100 - x)% Bi2Te3-x% Sb2Te3 (75 less than or equal to x less than or equal to 85) and 20% Bi2Te3-(80 - y)% Sb2Te3-gamma% Sb2Se3 (0 less than or equal to gamma less than or equal to 7) alloys were fabricated by mechanical alloying and hot pressing, and their thermoelectric properties were characterized. Among the hot-pressed (100 - x)% Bi2Te3-x% Sb2Te3 alloys, the 20% Bi2Te3-80% Sb2Te3 alloy exhibited a maximum figure-of-merit of 3.05 x 10(-3)/K. The Seebeck coefficient and the electrical resistivity of the hot-pressed 20% Bi2Te3-(80 - gamma) Sb2Te3-gamma% Sb2Se3 alloys increased with increasing the Sb2Se3 content due to the reduction of the hole concentration. The figure-of-merit of the hot-pressed 20% Bi2Te3-(80 - gamma)% Sb2Te3-gamma% Sb2Se3 alloys decreased from 3.05 x 10(-3)/K to 2.5 x 10(-3)/K with increasing the Sb2Se3 content up to 7 mol%, because the increment of the electrical resistivity was much larger than the decrement of the thermal conductivity and the increment of the Seebeck coefficient. (C) 2000 Elsevier Science Ltd. All rights reserved.