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Structural Evolution of High‐Performance Mn‐Alloyed Thermoelectric Materials: A Case Study of SnTe
Author(s) -
Sun Qiang,
Chen ZhiYu,
Li Meng,
Shi XiaoLei,
Xu ShengDuo,
Yin Yu,
Dargusch Matthew,
Zou Jin,
Ang Ran,
Chen ZhiGang
Publication year - 2021
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202100525
Subject(s) - thermoelectric materials , thermoelectric effect , materials science , condensed matter physics , phonon scattering , scanning transmission electron microscopy , thermal conductivity , scattering , phonon , transmission electron microscopy , dopant , chemical physics , nanotechnology , thermodynamics , doping , optoelectronics , chemistry , composite material , optics , physics
Mn alloying in thermoelectrics is a long‐standing strategy for enhancing their figure‐of‐merit through optimizing electronic transport properties by band convergence, valley perturbation, or spin‐orbital coupling. By contrast, mechanisms by which Mn contributes to suppressing thermal transports, namely thermal conductivity, is still ambiguous. A few precedent studies indicate that Mn introduces a series of hierarchical defects from the nano‐ to meso‐scale, leading to effective phonon scattering scoping a wide frequency spectrum. Due to insufficient insights at the atomic level, the theory remains as phenomenological and cannot be used to quantitatively predict the thermal conductivity of Mn‐alloyed thermoelectrics. Herein, by choosing the SnTe as a case study, aberration‐corrected transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM) to characterize the lattice complexity of Sn 1.02− x Mn x Te is employed. Mn as a “dynamic” dopant that plays an important role in SnTe with respect to different alloying levels or post treatments is revealed. The results indicate that Mn precipitates at x = 0.08 prior to reaching solubility (≈10 mol%), and then splits into Mn Sn substitution and γ‐MnTe hetero‐phases via mechanical alloying. Understanding such unique crystallography evolution, combined with a modified Debye‐Callaway model, is critical in explaining the decreased thermal conductivity of Sn 1.02− x Mn x Te with rational phonon scattering pathways, which should be applicable for other thermoelectric systems.