Cristallographic anisotropy control of n-type Bi-Te-Se thermoelectric materials via bulk mechanical alloying and shear extrusion

Abstract

The shear extrusion processing combined with bulk mechanical alloying is proposed to yield the n-type Bi-Te-Se material from elemental granules. It has well-developed texture so as to improve the electric conductivity and thermoelectric properties. The shear extrusion processing of (Bi 2Se3)0.05(Bi2Te3) 0.95 alloy green compact can afford the preferred orientation factor of anisotropic crystallographic structure: F = 0.67. The electric resistivity of (Bi2Se3)0.05(Bi2Te 3)0.95 is controlled to be 0.491 × 10-5 (Ωm), which is 0.2 times lower than that of hot-pressed specimen. Maximum power factor is achieved to be 3.31 × 10-3 (W/mK2) even without any dopants. The bending strength of the material produced in this work is also improved to be 166 MPa, 1.7 times higher than that of conventional hot-extruded specimens.