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<p>The increasing global energy demand and reliance on fossil fuels have exacerbated global warming, necessitating sustainable energy solutions. This study aims to explore the possibility of designing n-type and p-type TE materials from the Zr<sub>2</sub>FeNiSb<sub>2</sub> double half-Heusler (DhH) compound using targeted substitutions and compositional tuning. We engineered n-type and p-type compounds by substituting Nb at the Zr site (Zr<sub>1.9</sub>Nb<sub>0.1</sub>FeNiSb<sub>2</sub>) and Sn at the Sb site (Zr<sub>2</sub>FeNiSb<sub>1.9</sub>Sn<sub>0.1</sub>). Microstructural analysis indicated a predominance of the half-Heusler phase with minor Fe-rich secondary phases. To eliminate these secondary phases and establish a direct structure–property correlation, the Fe content was reduced and compensated with increased Ni content. However, increasing Ni tends to decompose the matrix in Zr<sub>2</sub>Fe<sub>0.9</sub>Ni<sub>1.1</sub>Sb<sub>2</sub>. Further Nb/Sn substitutions stabilized the microstructure without the adverse effects from Fe/Ni tuning. Seebeck coefficient measurements from near RT to 973&#xa0;K showed that all alloys except Zr<sub>2</sub>Fe<sub>0.9</sub>Ni<sub>1.1</sub>Sb<sub>1.9</sub>Sn<sub>0.1</sub> exhibited n-type behaviour, while this Sn-substituted alloy switched from p-type to n-type upon variation of Fe/Ni ratio. This study also defines the half-Heusler phase composition space, with Fe and Ni varying within ~ 15.64 to 17.39 at% and 15.90 to 18.84 at%, respectively, providing valuable insights for designing DhH-based TE materials.</p> Graphical abstract <p></p>

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Exploring composition space by Nb and Sn substitution, microstructure and Seebeck behaviour in Zr2FeNiSb2 double half-Heusler compound

  • 期刊论文

  • 发表日期：

    2025年1月9日

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  • Dharita Chandravanshi,
  • Dipanjan Kumar,
  • Y. Kawamura,
  • K. Ramesh,
  • N. Ravishankar,
  • Praveen C. Ramamurthy,
  • Kamanio Chattopadhyay

摘要

The increasing global energy demand and reliance on fossil fuels have exacerbated global warming, necessitating sustainable energy solutions. This study aims to explore the possibility of designing n-type and p-type TE materials from the Zr2FeNiSb2 double half-Heusler (DhH) compound using targeted substitutions and compositional tuning. We engineered n-type and p-type compounds by substituting Nb at the Zr site (Zr1.9Nb0.1FeNiSb2) and Sn at the Sb site (Zr2FeNiSb1.9Sn0.1). Microstructural analysis indicated a predominance of the half-Heusler phase with minor Fe-rich secondary phases. To eliminate these secondary phases and establish a direct structure–property correlation, the Fe content was reduced and compensated with increased Ni content. However, increasing Ni tends to decompose the matrix in Zr2Fe0.9Ni1.1Sb2. Further Nb/Sn substitutions stabilized the microstructure without the adverse effects from Fe/Ni tuning. Seebeck coefficient measurements from near RT to 973 K showed that all alloys except Zr2Fe0.9Ni1.1Sb1.9Sn0.1 exhibited n-type behaviour, while this Sn-substituted alloy switched from p-type to n-type upon variation of Fe/Ni ratio. This study also defines the half-Heusler phase composition space, with Fe and Ni varying within ~ 15.64 to 17.39 at% and 15.90 to 18.84 at%, respectively, providing valuable insights for designing DhH-based TE materials.

Graphical abstract