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High‐Pressure‐Sintering‐Induced Microstructural Engineering for an Ultimate Phonon Scattering of Thermoelectric Half‐Heusler Compounds
Author(s) -
He Ran,
Zhu Taishan,
Ying Pingjun,
Chen Jie,
Giebeler Lars,
Kühn Uta,
Grossman Jeffrey C.,
Wang Yumei,
Nielsch Kornelius
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.202102045
Subject(s) - thermoelectric effect , materials science , thermoelectric materials , phonon scattering , phonon , microstructure , thermal conductivity , sintering , grain size , scattering , condensed matter physics , nanotechnology , optoelectronics , composite material , thermodynamics , optics , physics
Thermal management is of vital importance in various modern technologies such as portable electronics, photovoltaics, and thermoelectric devices. Impeding phonon transport remains one of the most challenging tasks for improving the thermoelectric performance of certain materials such as half‐Heusler compounds. Herein, a significant reduction of lattice thermal conductivity (κ L ) is achieved by applying a pressure of ≈1 GPa to sinter a broad range of half‐Heusler compounds. Contrasting with the common sintering pressure of less than 100 MPa, the gigapascal‐level pressure enables densification at a lower temperature, thus greatly modifying the structural characteristics for an intensified phonon scattering. A maximum κ L reduction of ≈83% is realized for HfCoSb from 14 to 2.5 W m −1 K −1 at 300 K with more than 95% relative density. The realized low κ L originates from a remarkable grain‐size refinement to below 100 nm together with the abundant in‐grain defects, as determined by microscopy investigations. This work uncovers the phonon transport properties of half‐Heusler compounds under unconventional microstructures, thus showing the potential of high‐pressure compaction in advancing the performance of thermoelectric materials.