In situ generation of flower-like and microspherical dendrites to improve thermoelectric properties of p-type Bi0.46Sb1.54Te3

In order to obtain excellent thermoelectric properties, constructing three-dimensional flower-like dendrite and microspherical flocculated crystal nanostructures are considered to be an effective method to improve the performance. In this work, Bi0.46Sb1.54Te3-x wt% AgCuTe composite samples are synthesized through mechanical alloying. By SEM, we can directly observe the in situ generated 3D flower-like dendrites and micro-spherically flocculated crystals, that can provide a large number of nano interfaces and then reduce the thermal conductivity. At the same time, lattice defects of different sizes are formed in Bi0.46Sb1.54Te3 composites, resulting in further reduction of the lattice thermal conductivity. In addition, the presence of Ag and Cu can adjust the carrier concentration and enlarge the band gap, which results in a significantly enhanced Seebeck coefficient at higher temperature and a wider temperature range application of the material. Finally, a high ZT value of 1.46 at 425 K and the average ZT value of 1.31 at 300–500 K were achieved for Bi0.46Sb1.54Te3-0.1 wt% AgCuTe sample. This work opened up a new path for the commercial application of Bi2Te3-based thermoelectric materials.