Simultaneously Improved Thermoelectric and Mechanical Properties Driven by MgB₂ Doping in Bi_0.4Sb_1.6Te₃ Based Alloys

Bi₂Te₃-based alloys are the most mature and widely used thermoelectric materials since their zT value has been significantly improved in past decades. However, the poor mechanical strength and machinability derived from the easy cleavage along basal planes not only produce many scraps in the device fabrication process but also lead the devices unstable in the actual service. In this work, a tiny amount of MgB₂ is induced in the Bi_0.4Sb_1.6Te₃ alloy to simultaneously enhance the thermoelectric and mechanical properties. In detail, magnesium atoms occupy the bismuth/antimony sites to optimize the carrier concentration and suppress the bipolar effect, pushing the average zT value up to 1.16 ranging from 300 to 500 K, which catches up with the current highest level in p-type Bi₂Te₃-based materials. Moreover, the precipitation phase, boron nanoparticles, distributed at the grain boundaries can effectively improve the compressive strength from 166 to 239 MPa. The prominent thermoelectric and mechanical properties endow the materials with great potential for commercial applications.