Enhanced Thermoelectric Performance of NixBi0.5Sb1.5Te3via In Situ Formation of NiTe2 Channels

Abstract

In an endeavor to develop high figure of merit (ZT) thermoelectric materials for power generation and cooling applications, the in situ nano-inclusion formation led to improvement in thermoelectric performance. Herein, we studied the controlled Ni inclusion in the Bi0.5Sb1.5Te3 (BST) matrix with varying Ni concentrations, that is, NixBi0.5Sb1.5Te3 (x = 0, 0.01, 0.04, and 0.08). Structural and microscopic analyses showed a clear formation of multi-structured p-type Bi0.5Sb1.5Te3 with fine channels of NiTe2 and their interface, which forms a potential barrier of 0.26 eV, giving rise to a carrier filtering effect. The inclusion of optimized Ni concentration, that is, x = 0.04, in NixBi0.5Sb1.5Te3 and formation of NiTe2 channels has resulted in higher electrical conductivity of 900 S/cm and Seebeck coefficient of 210 μV/K simultaneously as compared to pristine BST. Further, Ni0.04Bi0.5Sb1.5Te3 has exhibited a ZT value of 1.4 at 373 K, which is 112% higher than the ZT (∼0.66 @ 373 K) of pristine BST.