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<p>This study presents a strategy to improve thermoelectric properties of substoichiometric pentagonal−columnar WO<sub>2.72</sub> oxides through microstructure engineering via the incorporation of Ta<sub>2</sub>O<sub>5</sub> inclusions as a secondary phase. A series of xTa<sub>2</sub>O<sub>5</sub>WO<sub>2.72</sub> oxides (x = 0–0.15) were synthesized via solid−state reaction in inert atmosphere. XRD and SEM analyses confirm the coexistence of Ta<sub>2</sub>O<sub>5</sub> segregations within the WO<sub>2.72</sub> crystal lattice structure without chemical reaction and reveal a nanorod−like grain morphology in the material. These structural modifications introduce significant phonon−scattering sites, reducing total thermal conductivity by half. Simultaneously, the Seebeck coefficient magnitude increases by 43% compared to the pristine phase, sufficient to compensate for the elevation in the resistivity caused by the introduction of the secondary−phase inclusions, thereby maintaining competitive power factors above 1000&#xa0;K. A peak <Emphasis Type="BoldItalic">zT</Emphasis> of 0.13 at 1073&#xa0;K is achieved for x = 0.15, nearly tripling the figure of pristine materials. The results highlight the effectiveness of microstructure−driven strategies for decoupling thermal and electronic transport in oxide thermoelectric.</p>

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Enhanced high-temperature thermoelectric performance of the n-type WO2.72 Ceramics: reduced lattice thermal conductivity via microstructure engineering

  • 期刊论文

  • 发表日期：

    2025年10月4日

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  • Tram Anh Huynh Ngoc,
  • Thanh Ngoc Bao Phan,
  • Quy Nguyen Ngoc Le,
  • Nhat Quang Minh Tran

摘要

This study presents a strategy to improve thermoelectric properties of substoichiometric pentagonal−columnar WO2.72 oxides through microstructure engineering via the incorporation of Ta2O5 inclusions as a secondary phase. A series of xTa2O5WO2.72 oxides (x = 0–0.15) were synthesized via solid−state reaction in inert atmosphere. XRD and SEM analyses confirm the coexistence of Ta2O5 segregations within the WO2.72 crystal lattice structure without chemical reaction and reveal a nanorod−like grain morphology in the material. These structural modifications introduce significant phonon−scattering sites, reducing total thermal conductivity by half. Simultaneously, the Seebeck coefficient magnitude increases by 43% compared to the pristine phase, sufficient to compensate for the elevation in the resistivity caused by the introduction of the secondary−phase inclusions, thereby maintaining competitive power factors above 1000 K. A peak zT of 0.13 at 1073 K is achieved for x = 0.15, nearly tripling the figure of pristine materials. The results highlight the effectiveness of microstructure−driven strategies for decoupling thermal and electronic transport in oxide thermoelectric.