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<p>Thermoelectric technology offers a promising route for converting industrial waste heat into useful electrical energy, encouraging research interests in cost-effective and scalable high-performance materials for intermediate-temperature applications. While multi-filled and charge-compensated CoSb<sub>3</sub> skutterudites have achieved impressive thermoelectric figure of merit, systematic studies on single Ce-filling via scalable wet-chemical routes without charge-compensating dopants remain limited. In this study, Ce<sub>x</sub>CoSb<sub>3</sub> (x = 0, 0.05, 0.1, 0.15) nanoparticles were synthesized by a solvothermal route and consolidated by a low-cost cold-press annealing approach, without doping at the Co or Sb site. Rietveld refinement of post-annealed powder X-ray diffraction (pXRD) patterns confirmed single-phase CoSb<sub>3</sub> for unfilled pristine sample, while Ce-filled compositions exhibited minor residual CoSb<sub>2</sub> phase below 10 wt%. Transmission electron microscope (TEM) confirmed the nanoscale particle dimensions, with high-resolution TEM (HRTEM) image depicting lattice fringe spacings consistent with the (301) and (110) planes of cubic CoSb<sub>3</sub>. XPS verified Ce<sup>3+</sup> incorporation into the skutterudite cages, contributing to reduced electrical resistivity through partial carrier compensation, while Raman spectroscopy confirmed Sb<sub>4</sub> ring distortion from the rattling effect of Ce fillers. Thermoelectric evaluation across 323-673&#xa0;K revealed that Ce<sub>0.15</sub>CoSb<sub>3</sub> demonstrated the highest power factor of 98 µW‧m<sup>− 1</sup>‧K<sup>− 2</sup> at 623&#xa0;K, and Ce<sub>0.05</sub>CoSb<sub>3</sub> exhibited ultralow thermal conductivity of 0.50&#xa0;W‧m<sup>− 1</sup>‧K<sup>− 1</sup> at 623&#xa0;K, which is among the lowest reported for solvothermally synthesized CoSb<sub>3</sub>. These properties yielded maximum zT values of 0.08 and 0.06 for Ce<sub>0.15</sub>CoSb<sub>3</sub> and Ce<sub>0.05</sub>CoSb<sub>3</sub>, respectively at 623&#xa0;K, representing 67% and 25% improvements over unfilled CoSb<sub>3</sub> (zT = 0.048). The current study establishes a meaningful baseline for Ce-filled CoSb<sub>3</sub> via solvothermal synthesis and cold-press annealing.</p> Graphical abstract <p></p>

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Low-cost solvothermal synthesis of Ce-filled CoSb3 skutterudites via cold-press annealing: structure, transport and thermoelectric properties

  • 期刊论文

  • 发表日期：

    2026年7月13日

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  • R. Swetha,
  • M. Uday Kumar,
  • Thang Bach Phan,
  • Hoa Thi Lai,
  • B. V. Sahana,
  • Latha Kumari

摘要

Thermoelectric technology offers a promising route for converting industrial waste heat into useful electrical energy, encouraging research interests in cost-effective and scalable high-performance materials for intermediate-temperature applications. While multi-filled and charge-compensated CoSb3 skutterudites have achieved impressive thermoelectric figure of merit, systematic studies on single Ce-filling via scalable wet-chemical routes without charge-compensating dopants remain limited. In this study, CexCoSb3 (x = 0, 0.05, 0.1, 0.15) nanoparticles were synthesized by a solvothermal route and consolidated by a low-cost cold-press annealing approach, without doping at the Co or Sb site. Rietveld refinement of post-annealed powder X-ray diffraction (pXRD) patterns confirmed single-phase CoSb3 for unfilled pristine sample, while Ce-filled compositions exhibited minor residual CoSb2 phase below 10 wt%. Transmission electron microscope (TEM) confirmed the nanoscale particle dimensions, with high-resolution TEM (HRTEM) image depicting lattice fringe spacings consistent with the (301) and (110) planes of cubic CoSb3. XPS verified Ce3+ incorporation into the skutterudite cages, contributing to reduced electrical resistivity through partial carrier compensation, while Raman spectroscopy confirmed Sb4 ring distortion from the rattling effect of Ce fillers. Thermoelectric evaluation across 323-673 K revealed that Ce0.15CoSb3 demonstrated the highest power factor of 98 µW‧m− 1‧K− 2 at 623 K, and Ce0.05CoSb3 exhibited ultralow thermal conductivity of 0.50 W‧m− 1‧K− 1 at 623 K, which is among the lowest reported for solvothermally synthesized CoSb3. These properties yielded maximum zT values of 0.08 and 0.06 for Ce0.15CoSb3 and Ce0.05CoSb3, respectively at 623 K, representing 67% and 25% improvements over unfilled CoSb3 (zT = 0.048). The current study establishes a meaningful baseline for Ce-filled CoSb3 via solvothermal synthesis and cold-press annealing.

Graphical abstract