Open AccessLow Sound Velocity Contributing to the High Thermoelectric Performance of Ag 8 SnSe 6
Author(s) -
Li Wen,
Lin Siqi,
Ge Binghui,
Yang Jiong,
Zhang Wenqing,
Pei Yanzhong
Publication year - 2016
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201600196
Subject(s) - thermoelectric effect , thermoelectric materials , materials science , phonon , thermal conductivity , condensed matter physics , figure of merit , mean free path , phonon scattering , semiconductor , doping , scattering , engineering physics , optoelectronics , thermodynamics , physics , composite material , optics
Conventional strategies for advancing thermoelectrics by minimizing the lattice thermal conductivity focus on phonon scattering for a short mean free path. Here, a design of slow phonon propagation as an effective approach for high‐performance thermoelectrics is shown. Taking Ag 8 SnSe 6 as an example, which shows one of the lowest sound velocities among known thermoelectric semiconductors, the lattice thermal conductivity is found to be as low as 0.2 W m −1 K −1 in the entire temperature range. As a result, a peak thermoelectric figure of merit zT > 1.2 and an average zT as high as ≈0.8 are achieved in Nb‐doped materials, without relying on a high thermoelectric power factor. This work demonstrates not only a guiding principle of low sound velocity for minimal lattice thermal conductivity and therefore high zT , but also argyrodite compounds as promising thermoelectric materials with weak chemical bonds and heavy constituent elements.