Thermoelectric properties of N-type Bi-2(Te1-xSex)(3) fabricated by mechanical alloying and hot pressing

Abstract

Thermoelectric properties of polycrystalline Bi-2(Te1-xSex)(3) (0.05 less than or equal to x less than or equal to 0.25), fabricated by mechanical alloying and hot pressing, have been investigated. Formation of n-type Bi-2(Te-0.9 Se-0.1)(3) alloy powders was completed by mechanical alloying for 3 hours at ball-to-material ratio of 5 : 1, and processing time for Bi-2(Te1-xSex)(3) formation increased with Bi2Se3 content x. Figure-of-merit of Bi-2(Te0.9Se0.1) was markedly increased by hot pressing at temperatures above 45O degrees C, and maximum value of 1.9 x 10(-3)/K was obtained by hot pressing at 550 degrees C. With addition of 0.015 wt% Bi as acceptor dopant, figure-of-merit of Bi-2(Te0.9Se0.1)(3), hot pressed at 550 degrees C, could be improved to 2.1 x 10(-3)/K. When Bi-2(Te1-xSex)(3) was hot pressed at 550 degrees C, figure-of-merit increased from 1.14 x 10(-3)/K to 1.92 x 10(-3)/K with increasing Bi2Se3 content x from 0.05 to 0.15, and then decreased to 1.30 x 10(-3)/K for x = 0.25 composition.