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<p>Developing high-performance near-room-temperature thermoelectric materials is crucial for solid-state cooling and low-grade waste heat recovery. While n-type Mg<sub>3</sub>(Sb, Bi)<sub>2</sub> has emerged as a promising candidate, its performance is fundamentally bottlenecked by the strong coupling of charge and heat transport, particularly the restricted carrier mobility originating from highly localized polar covalent bonds. Herein, we propose a synergistic strategy that manipulates chemical bond polarity and constructs multiscale defect architectures via Ni doping to decouple electron and phonon transport. First-principles calculations and structural analyses reveal that substituting Mg with the more electronegative Ni significantly reduces the cation-anion electronegativity difference. This effectively weakens the polarity of the Mg-(Sb, Bi) bonds and drives an antibonding-state-induced electron delocalization, yielding a remarkable ∼49.5% enhancement in room-temperature carrier mobility (up to 265.69 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>). Concurrently, exceeding the solid solubility limit of Ni triggers the spontaneous formation of Ni-rich nanoprecipitates. These precipitates, coupled with point defects and local lattice distortions, establish a robust multiscale scattering network that effectively suppresses the lattice thermal conductivity to 0.74 W m<sup>−1</sup> K<sup>−1</sup> at 300 K. Consequently, the optimized Mg<sub>3.3</sub>Sb<sub>0.5</sub>Bi<sub>1.497</sub>Te<sub>0.003</sub>Ni<sub>0.01</sub> sample achieves an exceptional room-temperature power factor of ∼31.61 µW cm<sup>−1</sup> K<sup>−2</sup>, culminating in a high room-temperature <i>ZT</i> of 0.84 and a peak <i>ZT</i> of 1.10 at 423 K. This work not only highlights the potential of n-type Mg<sub>3</sub>(Sb, Bi)<sub>2</sub> for near-room-temperature applications but also establishes a universal paradigm for optimizing polar thermoelectric semiconductors through electronegativity-driven bond engineering.</p>

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Manipulating bond polarity and multiscale defect architectures for high-performance near-room-temperature Mg3(Sb, Bi)2 thermoelectrics

  • 期刊论文

  • 发表日期：

    2026年6月29日

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  • Yanqi Huang,
  • Zehao Lin,
  • Minwen Yang,
  • Jiahao Jiang,
  • Junyu Lin,
  • Yukun Ma,
  • Qing Cao,
  • Fuqiang Tang,
  • Hui Zhang,
  • Jing Shuai

摘要

Developing high-performance near-room-temperature thermoelectric materials is crucial for solid-state cooling and low-grade waste heat recovery. While n-type Mg3(Sb, Bi)2 has emerged as a promising candidate, its performance is fundamentally bottlenecked by the strong coupling of charge and heat transport, particularly the restricted carrier mobility originating from highly localized polar covalent bonds. Herein, we propose a synergistic strategy that manipulates chemical bond polarity and constructs multiscale defect architectures via Ni doping to decouple electron and phonon transport. First-principles calculations and structural analyses reveal that substituting Mg with the more electronegative Ni significantly reduces the cation-anion electronegativity difference. This effectively weakens the polarity of the Mg-(Sb, Bi) bonds and drives an antibonding-state-induced electron delocalization, yielding a remarkable ∼49.5% enhancement in room-temperature carrier mobility (up to 265.69 cm2 V−1 s−1). Concurrently, exceeding the solid solubility limit of Ni triggers the spontaneous formation of Ni-rich nanoprecipitates. These precipitates, coupled with point defects and local lattice distortions, establish a robust multiscale scattering network that effectively suppresses the lattice thermal conductivity to 0.74 W m−1 K−1 at 300 K. Consequently, the optimized Mg3.3Sb0.5Bi1.497Te0.003Ni0.01 sample achieves an exceptional room-temperature power factor of ∼31.61 µW cm−1 K−2, culminating in a high room-temperature ZT of 0.84 and a peak ZT of 1.10 at 423 K. This work not only highlights the potential of n-type Mg3(Sb, Bi)2 for near-room-temperature applications but also establishes a universal paradigm for optimizing polar thermoelectric semiconductors through electronegativity-driven bond engineering.