Thermoelectric properties of p-type (Bi1-xSbx)(2)Te-3 fabricated by mechanical alloying process

Abstract

Thermoelectric properties of polycrystalline (Bi1-xSbx)(2)Te-3 (0.75 less than or equal to x less than or equal to 0.85), fabricated by mechanical alloying and hot pressing methods, have been investigated. Formation of (Bi0.25Sb0.75)(2)Te-3 alloy powder was completed by mechanical alloying for 5 hours at ball-to-material ratio of 5 : 1, and processing time for (Bi1-xSbx)(2)Te-3 formation increased with Sb2Te3 content x. When (Bi0.25Sb0.75)(2)Te-3 was hot pressed at temperatures ranging from 300 degrees C to 550 degrees C for 30 minutes, figure-of-merit increased with hot pressing temperature and maximum value of 2.8 x 10(-3)/K could be obtained by hot pressing at 550 degrees C. When hot pressed at 550 degrees C, (Bi0.2Sb0.8)(2)Te-3 exhibited figure-of-merit of 2.92 x 10(-3)/K, which could be improved to 2.97 x 10(-3)/K with addition of 1 wt% Sb as acceptor dopant.