Enhanced thermoelectric performance through homogenously dispersed MnTe nanoparticles in p-type Bi_0.52Sb_1.48Te₃ nanocomposites

In this work, we report that the thermoelectric properties of Bi_0.52Sb_1.48Te₃ alloy can be enhanced by being composited with MnTe nano particles (NPs) through a combined ball milling and spark plasma sintering (SPS) process. The addition of MnTe into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phonon scattering between Bi_0.52Sb_1.48Te₃ and MnTe NPs, and enhance the electrical transport properties by optimizing the hole concentration through partial Mn²⁺ acceptor doping on the Bi³⁺ sites of the host lattice. It is observed that the lattice thermal conductivity decreases with increasing the percentage of MnTe and milling time in a temperature range from 300 K to 500 K, which is consistent with the increasing of interfaces. Meanwhile, the bipolar effect is constrained to high temperatures, which results in the figure of merit zT peak shifting toward higher temperature and broadening the zT curves. The engineering zT is obtained to be 20% higher than that of the pristine sample for the 2-mol% MnTe-added composite at a temperature gradient of 200 K when the cold end temperature is set to be 300 K. This result indicates that the thermoelectric performance of Bi_0.52Sb_1.48Te₃ can be considerably enhanced by being composited with MnTe NPs.