Synergistic Grain Boundary and Phonon Engineering Enables Ultrahigh Thermoelectric Performance in Mg 3 (Sb, Bi) 2 ‐Based Materials
Abstract
Thermoelectric Mg 3 (Sb, Bi) 2 has emerged as a rising star in virtue of its promising thermoelectric performance and abundant constituent elements. However, its practical application is hindered by challenges in synthesis and the strong coupling between electrical and thermal transport properties. Herein, we propose a dual‐pronged strategy that combines grain boundary engineering and phonon engineering to decouple electron and phonon transport in Mg 3 (Sb, Bi) 2 . By employing a tantalum‐tube encapsulated melting technique together with Cu doping, the grain size is markedly increased to ∼25 µm, effectively suppressing carrier grain boundary scattering and enabling single‐crystal‐like electrical transport with a high carrier mobility exceeding 200 cm 2 V −1 s −1 . Meanwhile, atomic‐scale alloy disorder and nanoscale Mg 2 Cu precipitates introduce strong phonon scattering, leading to an ultralow lattice thermal conductivity of 0.36 W m −1 K −1 . Eventually, a peak zT of 1.9 at 750 K and a high conversion efficiency of 10.6% at ΔT = 488 K are achieved, demonstrating the competitive performance of these materials and devices. This study not only provides new insights into the manipulation of grain boundary scattering, but also demonstrates the great promise of Mg 3 (Sb, Bi) 2 for waste‐heat harvesting.
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BibTeX
@article{lei2026synergistic,
title = {{Synergistic Grain Boundary and Phonon Engineering Enables Ultrahigh Thermoelectric Performance in Mg 3 (Sb, Bi) 2 ‐Based Materials}},
author = {Jingdan Lei and Kai Xu and Kunpeng Zhao and Junzhuo Zhou and Haotian Gao and Yifan Yuan and Tian‐ran Wei and Min Zhu and Qihao Zhang and Franck Gascoin and Xun Shi},
journal = {Advanced Science},
year = {2026},
month = aug,
doi = {10.1002/advs.77449},
url = {https://hal.science/hal-05748570v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Synergistic Grain Boundary and Phonon Engineering Enables Ultrahigh Thermoelectric Performance in Mg 3 (Sb, Bi) 2 ‐Based Materials
AU - Jingdan Lei
AU - Kai Xu
AU - Kunpeng Zhao
AU - Junzhuo Zhou
AU - Haotian Gao
AU - Yifan Yuan
AU - Tian‐ran Wei
AU - Min Zhu
AU - Qihao Zhang
AU - Franck Gascoin
AU - Xun Shi
PY - 2026
DA - 2026/08/30
JO - Advanced Science
DO - 10.1002/advs.77449
UR - https://hal.science/hal-05748570v1
AB - Thermoelectric Mg 3 (Sb, Bi) 2 has emerged as a rising star in virtue of its promising thermoelectric performance and abundant constituent elements. However, its practical application is hindered by challenges in synthesis and the strong coupling between electrical and thermal transport properties. Herein, we propose a dual‐pronged strategy that combines grain boundary engineering and phonon engineering to decouple electron and phonon transport in Mg 3 (Sb, Bi) 2 . By employing a tantalum‐tube encapsulated melting technique together with Cu doping, the grain size is markedly increased to ∼25 µm, effectively suppressing carrier grain boundary scattering and enabling single‐crystal‐like electrical transport with a high carrier mobility exceeding 200 cm 2 V −1 s −1 . Meanwhile, atomic‐scale alloy disorder and nanoscale Mg 2 Cu precipitates introduce strong phonon scattering, leading to an ultralow lattice thermal conductivity of 0.36 W m −1 K −1 . Eventually, a peak zT of 1.9 at 750 K and a high conversion efficiency of 10.6% at ΔT = 488 K are achieved, demonstrating the competitive performance of these materials and devices. This study not only provides new insights into the manipulation of grain boundary scattering, but also demonstrates the great promise of Mg 3 (Sb, Bi) 2 for waste‐heat harvesting.
SN - 2198-3844
ER -