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 tha n or equal to 85) and 20% Bi2Te3-(80 - y)% Sb2Te3-gamma% Sb2Se3 (0 less tha n or equal to gamma less than or equal to 7) alloys were fabricated by mech anical alloying and hot pressing, and their thermoelectric properties were characterized. Among the hot-pressed (100 - x)% Bi2Te3-x% Sb2Te3 alloys, th e 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 ho t-pressed 20% Bi2Te3-(80 - gamma) Sb2Te3-gamma% Sb2Se3 alloys increased wit h increasing the Sb2Se3 content due to the reduction of the hole concentrat ion. 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 e lectrical resistivity was much larger than the decrement of the thermal con ductivity and the increment of the Seebeck coefficient. (C) 2000 Elsevier S cience Ltd. All rights reserved.