am9b10207_si_001.pdf (1.5 MB)
Reducing Lattice Thermal Conductivity of MnTe by Se Alloying toward High Thermoelectric Performance
journal contribution
posted on 2019-07-25, 20:15 authored by Jinfeng Dong, Fu-Hua Sun, Huaichao Tang, Kei Hayashi, Hezhang Li, Peng-Peng Shang, Yuzuru Miyazaki, Jing-Feng LiLead-free manganese
telluride has been considered to be a promising
candidate for mid-temperature thermoelectric materials. In this work,
we report point defect scattering-induced reduction of thermal conductivity
in MnTe with Se alloying, fabricated by a facile method combining
mechanical alloying and spark plasma sintering. A low lattice thermal
conductivity of 0.56 W/mK was obtained for MnTe0.92Se0.08, which is quite close to the amorphous limits. A detailed
Debye model analysis reveals the underlying mechanism of phonon scattering
and well predicts the thermal conductivity with different contents
of Se. Meanwhile, a slight increase of carrier concentration was also
observed after Se alloying, accompanied by a variation of energy gap
that may be associated with the competition among anions in trapping
charges. Further Na doping leads to enhanced electrical transport
properties, achieving a maximum ZT value of 1.03
at 873 K. An average ZT of 0.52 and a calculated
efficiency of more than 9% also suggest the promising application
of MnTe at medium temperatures.