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<p>Introducing appropriate donor dopants in N-Type Mg<sub>3</sub>Sb<sub>1.5</sub>Bi<sub>0.5</sub>-based compounds to enhance carrier concentration (<i>n</i>) is a critical strategy for improving thermoelectric (TE) performance. In this study, we investigated the effects of co-doping of Nd at the Mg site and Se at the Bi site on the electronic band structure of Mg<sub>3</sub>Sb<sub>1.5</sub>Bi<sub>0.5</sub>-based compounds. First-principles calculations revealed that Nd and Se co-doping shifted the Fermi level into the conduction band and narrowed the bandgap from 0.21&#xa0;eV to 0.09&#xa0;eV, thereby increasing electron band contributions and enhancing electrical conductivity (<i>σ</i>). A high carrier concentration (<i>n</i>) of 6.5 × 10<sup>19</sup>&#xa0;cm<sup>−3</sup> was achieved, leading to a power factor (<i>PF</i>) exceeding 20&#xa0;μW&#xa0;cm<sup>−1</sup>&#xa0;K<sup>−2</sup>. Additionally, Nd and Se co-doping introduced crystal defects and strains, which effectively scatter phonons. The presence of multiple phonon scattering mechanisms significantly reduced the lattice thermal conductivity (<i>κ</i><sub>L</sub>) to 0.42&#xa0;W&#xa0;m<sup>−1</sup>&#xa0;K<sup>−1</sup>, resulting in a peak dimensionless figure of merit (<i>ZT</i>) of approximately 1.83 at 673&#xa0;K in Mg<sub>3.19</sub>Nd<sub>0.01</sub>Sb<sub>1.5</sub>Bi<sub>0.49</sub>Se<sub>0.01</sub>. Our findings demonstrate that the rare earth element Nd, as an efficient N-Type dopant, plays a pivotal role in modulating electron concentration.</p> Graphical Abstract <p></p>

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Enhanced Thermoelectric Performances of N-Type Mg3Sb1.5Bi0.5-Based Zintl Compounds Through Energy Band Engineering by Nd and Se Co-Doping

  • 期刊论文

  • 发表日期：

    2025年4月23日

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  • Huijuan Wang,
  • Hang Liu,
  • Guocai Yuan,
  • Runyu Wang,
  • Xiaobo Lei,
  • Xin Yan,
  • Qinyong Zhang,
  • Ruonan Min,
  • Biyou Peng,
  • Lihong Huang

摘要

Introducing appropriate donor dopants in N-Type Mg3Sb1.5Bi0.5-based compounds to enhance carrier concentration (n) is a critical strategy for improving thermoelectric (TE) performance. In this study, we investigated the effects of co-doping of Nd at the Mg site and Se at the Bi site on the electronic band structure of Mg3Sb1.5Bi0.5-based compounds. First-principles calculations revealed that Nd and Se co-doping shifted the Fermi level into the conduction band and narrowed the bandgap from 0.21 eV to 0.09 eV, thereby increasing electron band contributions and enhancing electrical conductivity (σ). A high carrier concentration (n) of 6.5 × 1019 cm−3 was achieved, leading to a power factor (PF) exceeding 20 μW cm−1 K−2. Additionally, Nd and Se co-doping introduced crystal defects and strains, which effectively scatter phonons. The presence of multiple phonon scattering mechanisms significantly reduced the lattice thermal conductivity (κL) to 0.42 W m−1 K−1, resulting in a peak dimensionless figure of merit (ZT) of approximately 1.83 at 673 K in Mg3.19Nd0.01Sb1.5Bi0.49Se0.01. Our findings demonstrate that the rare earth element Nd, as an efficient N-Type dopant, plays a pivotal role in modulating electron concentration.

Graphical Abstract