Thermoelectric properties of the p-type Bi 2Te 3–Sb 2Te 3–Sb 2Se 3 alloys fabricated by mechanical alloying and hot pressing

Abstract

The p-type (100− x)% Bi 2Te 3– x% Sb 2Te 3 (75≤ x≤85) and 20% Bi 2Te 3–(80− y)% Sb 2Te 3– y% Sb 2Se 3 (0≤ y≤7) alloys were fabricated by mechanical alloying and hot pressing, and their thermoelectric properties were characterized. Among the hot-pressed (100− x)% Bi 2Te 3– x% Sb 2Te 3 alloys, the 20% Bi 2Te 3–80% Sb 2Te 3 alloy exhibited a maximum figure-of-merit of 3.05×10 −3/K. The Seebeck coefficient and the electrical resistivity of the hot-pressed 20% Bi 2Te 3–(80− y)% Sb 2Te 3– y% Sb 2Se 3 alloys increased with increasing the Sb 2Se 3 content due to the reduction of the hole concentration. The figure-of-merit of the hot-pressed 20% Bi 2Te 3–(80− y)% Sb 2Te 3– y% Sb 2Se 3 alloys decreased from 3.05×10 −3/K to 2.5×10 −3/K with increasing the Sb 2Se 3 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.