Enhanced thermoelectric performance through homogenously dispersed MnTe nanoparticles in p-type Bi_(0.52)Sb_(1.48)Te_3 nanocomposites

In this work,we report that the thermoelectric properties of Bi（0.52）Sb（1.48）Te3alloy can be enhanced by being composited with Mn Te nano particles（NPs）through a combined ball milling and spark plasma sintering（SPS）process.The addition of Mn Te into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phononscattering between Bi（0.52）Sb（1.48）Te3 and MnTe NPs,and enhance the electrical transport properties by optimizing the hole concentration through partial Mn^2＋ acceptor doping on the Bi^3＋ sites of the host lattice.It is observed that the lattice thermal conductivity decreases with increasing the percentage of Mn Te and milling time in a temperature range from 300 Kto 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 z T peak shifting toward higher temperature and broadening the z T curves.The engineering z T is obtained to be 20%higher than that of the pristine sample for the 2-mol%Mn Te-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 Bi0.52Sb1.48Te3 can be considerably enhanced by being composited with Mn Te NPs.

Decoupling of thermoelectric transport performance of Ag doped and Se alloyed tellurium induced by carrier mobility compensation

Alloying with Se is proved to be feasible to suppress the lattice thermal conductivity(κL)of tellurium by introducing multidimensional lattice defects.However,extra ionization impurity centers induced by Se alloying are harmful to the electric transport properties of the matrix.In this paper,we propose that the incorporation of Ag could successfully compensate the lost carrier mobility(μH)due to Se alloying through the regulation of microstructure,resulting in the higher power factor(PF)than that of samples without Ag.After composition optimization,theκLdecreased from 1.29 W m^(-1)K^(-1) of Te_(0.99)Sb_(0.01) to 1.05 W m^(-1)K^(-1) of Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01) at 350 K,while the PF remained unchanged or even slightly increased.Benefit from the synergistic effect of carrier mobility compensation and phonon scattering,a maximum z T of 0.91 at 573 K and an average z T of 0.57(between 298 and 573 K)are achieved in Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01).This work presents a new strategy for decoupling the thermal and electric parameters of Te-based thermoelectric materials.