Study of anisotropic thermal conductivity in textured thermoelectric alloys by Raman spectroscopy

Abstract

Polycrystalline p-type Sb1.5Bi0.5Te3 (SBT) and n-type Bi2Te2.7Se0.3 (BTS) compounds possessing layered crystal structure show anisotropic electronic and thermal transport properties.

Optimizing Room-Temperature Thermoelectric Performance of n-Type Bi2Te2.7Se0.3

“…Bi 2 Te 3 -based compounds belong to the rhombohedral crystal system with the Te (1) –Bi–Te (2) –Bi–Te (1) atomic layer as the basic unit repeatedly arranged in the c -axis direction. , The interlayer is connected by covalent and ion bonds, while the adjacent layers are connected by a weak van der Waals force, leading to the facile cleavage along the in-plane direction. The special layered crystal structure allows the thermal and electrical properties of the Bi 2 Te 3 -based compounds to exhibit strong anisotropy in different directions. − Overall, the TE performance in the vertical hot pressing (HP) direction is higher than that in parallel to the HP direction. Bi 2 Te 3 -based alloys exhibit zT ≈ 1, and the TE properties of n-type are generally below p-type. − Over the coming years, synthesis methods such as solid-phase reaction, − ball milling, , zone melting, − and preparation methods such as HP − or spark plasma sintering (SPS) − have been widely used to enhance zT of Bi 2 Te 3 -based alloys.…”