Crystallographic 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 andthermoelectric properties. The shear extrusion processing of (Bi 2 Se 3 ) 0 . 0 5 (Bi 2 Te 3 ) 0 . 9 5 alloy green compact can afford the preferred orientation factor of anisotropic crystallographic structure: F = 0.67. The electric resistivity of (Bi 2 Se 3 ) 0 . 0 5 (Bi 2 Te 3 ) 0 . 9 5 is controlled to be 0.491 x 10 - 5 (Ωm), which is 0.2 times lower than that of hot-pressed specimen. Maximum power factor is achieved to be 3.31 x 10 - 3 (W/mK 2 ) even without any dopants. The bending strength of the material produced in this work is also improved to be 166MPa, 1.7 times higher than that of conventional hot-extruded specimens.