Realizing High Thermoelectric Performance in Sb-Doped AgTe Compounds with a Low-Temperature Monoclinic Structure.

To recover the low-grade waste heat (300-500 K), it is of urgent importance to develop and improve the thermoelectric performance at a low-temperature region. Herein, we have realized a record high value of 1.4 at 410 K and a record high average value of 0.6 in the temperature interval from 300 to 400 K for Sb-doped AgSbTe ( = 0-0.03) compounds, which show an improvement of 180 and 120% compared to pristine AgTe, respectively. Sb doping increases the carrier concentration and electrical conductivity, leading to a remarkable improvement of electrical transport properties. The AgSbTe sample obtains the maximal power factor of 1.07 × 10 W m K at 410 K, which is increased by 80% in comparison to that of pristine AgTe. Moreover, as a result of the intensified alloying phonon scattering by Sb doping, AgSbTe possesses the minimum lattice thermal conductivity of 0.35 W m K at 300 K, which demonstrates a decline of 57% compared to that of pristine AgTe. All of these produce a great enhancement on the thermoelectric performance of AgTe materials, which shows great potential in the application of recycling the low-grade waste heat at a low-temperature region.