Optimized thermoelectric properties of Bi0.48Sb1.52Te3/BN composites

Abstract

Bi_xSb_2−xTe₃ and Bi₂Te_3−xSe_x alloys demonstrate the state-of-the-art thermoelectric (TE) performances at around 300 K and have realized wide applications in TE refrigerators. However, the ZT values of the zone-melted materials have not been ideal for a long time. Aiming at the target of improving TE properties, we prepared p-type Bi_0.48Sb_1.52Te_3−x wt% BN composites. The measurement results indicate that the addition of BN particles can effectively increase the thermopowers and maintain relatively high carrier mobilities, leading to a noticeably improved power factor of 53 μW cm⁻¹ K⁻² at 300 K. Moreover, the total thermal conductivity is significantly suppressed because of the decreased electrical conductivity and the introduced phonon scattering centers. Consequently, a maximum ZT value of 1.3 is obtained at 375 K in the x = 0.10 wt% composite, while the Vickers hardness and compressive strength are improved to 0.31 GPa and 8.8 MPa, respectively. This study demonstrates that a small amount of BN addition is a credible scheme to synergistically optimize both the TE and mechanical performances of p-type Bi₂Te₃-based materials.