High power factor and mechanical properties of Bi1-xSbx alloys enabled by redensification of crystal slabs

The low-cost Bi_1-xSb_x crystal has been considered the best low-temperature material for its high electrical properties, which also can generate high effective thermal conductivity, revealing a high potential in heat dissipation. However, the weak mechanical strength hinders practical applications. Herein, we firstly grew the Bi_1-xSb_x crystal by the Bridgeman method, then cleaved the crystal into slabs with different sizes for hot-pressing. The obtained materials exhibited a high bending strength of 72 MPa, which is twofold that of Bi_1-xSb_x [001]-direction. Furthermore, the hot-pressed Bi_1-xSb_x samples show high electrical conductivities, being similar to those of the single crystals, resulting in the high record power factor of 78 μW·cm^-1·K^-2 @110 K and 38 μW·cm^-1·K^-2 @300 K among the hot-pressed poly-crystalline Bi_1-xSb_x. This high electrical performance is beneficial to the applications of heat dissipation. Therefore, this work proves an effective way to simultaneously improve the mechanical and thermoelectric properties of Bi_1-xSb_x alloys.