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<p>Lead chalcogenides are regarded as highly prospective mid-temperature thermoelectric materials due to their excellent performance. Pseudo-binary PbTe-PbS compounds, a representative system, exhibit intrinsically low lattice thermal conductivities originating from phase separation. However, most previous studies have primarily relied on empirical sample fabrication, lacking a systematic thermodynamics-guided design. In this work, isothermal sections of the pseudo-binary PbTe-PbS phase diagram were constructed using the diffusion couple method. The miscibility gap of PbTe<sub>1−<i>x</i></sub>S<sub><i>x</i></sub> at 873 K was determined to be <i>x</i> = 0.15–0.94. Guided by the experimental phase diagram, a series of 2 at.% Na-doped p-type samples were synthesized. A peak <i>zT</i> of ∼1.9 at 773 K and an average <i>zT</i> exceeding 1.0 were achieved in Pb<sub>0.98</sub>Na<sub>0.02</sub>Te<sub>0.84</sub>S<sub>0.16</sub>, which is located in the nucleation-and-growth region on the PbTe-rich side, owing to its ultralow lattice thermal conductivity of ∼0.55 W m<sup>−1</sup> K<sup>−1</sup> at 773 K. Microstructural analysis revealed that dislocations at the PbTe-rich and PbS-rich interfaces serve as effective phonon scattering centers, while semi-coherent phase boundaries preserve high carrier mobilities, enhancing thermoelectric performance in this equilibrium phase region.</p>

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Revisiting the high-performance p-type PbTe-PbS thermoelectric materials through phase diagram design

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Zixuan Fu,
  • Wenhua Xue,
  • Xiaodong Wang,
  • Baopeng Ma,
  • Sichen Duan,
  • Xiaofang Li,
  • Yumei Wang,
  • Feng Cao,
  • Jun Mao,
  • Qian Zhang

摘要

Lead chalcogenides are regarded as highly prospective mid-temperature thermoelectric materials due to their excellent performance. Pseudo-binary PbTe-PbS compounds, a representative system, exhibit intrinsically low lattice thermal conductivities originating from phase separation. However, most previous studies have primarily relied on empirical sample fabrication, lacking a systematic thermodynamics-guided design. In this work, isothermal sections of the pseudo-binary PbTe-PbS phase diagram were constructed using the diffusion couple method. The miscibility gap of PbTe1−xSx at 873 K was determined to be x = 0.15–0.94. Guided by the experimental phase diagram, a series of 2 at.% Na-doped p-type samples were synthesized. A peak zT of ∼1.9 at 773 K and an average zT exceeding 1.0 were achieved in Pb0.98Na0.02Te0.84S0.16, which is located in the nucleation-and-growth region on the PbTe-rich side, owing to its ultralow lattice thermal conductivity of ∼0.55 W m−1 K−1 at 773 K. Microstructural analysis revealed that dislocations at the PbTe-rich and PbS-rich interfaces serve as effective phonon scattering centers, while semi-coherent phase boundaries preserve high carrier mobilities, enhancing thermoelectric performance in this equilibrium phase region.