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<p>We conducted a comprehensive first-principles investigation of the structural, electronic, mechanical, optical, and thermoelectric properties of FeNbX (X = P, As, Bi) half-Heusler compounds using density functional theory. The structural optimizations showed that all the compounds are more stable in the Type-1 atomic arrangement, with a non-magnetic ground state. They also have negative formation energies, which confirms their thermodynamic stability. The lattice constants increase systematically from FeNbP to FeNbBi, in line with the increasing atomic radii of the X elements. Electronic band structure analysis using the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential indicates indirect bandgaps ranging from 0.62&#xa0;eV to 0.79&#xa0;eV, with FeNbBi having the largest gap due to relativistic effects. Density of states analysis highlights that the Fe-d and Nb-d orbitals dominate the states near the Fermi level, while the X-p orbitals contribute significantly depending on the mass of the X atom. Phonon dispersion calculations confirm the dynamic stability of the three compounds. Furthermore, mechanical analysis based on elastic constants attests to their mechanical robustness and moderate ductility. Optical studies reveal high static dielectric constants, strong absorption in the visible and ultraviolet ranges, and enhanced optical response in FeNbBi, particularly in the near-infrared. The assessment of thermoelectric performance, based on Boltzmann transport theory, reveals high Seebeck coefficients. FeNbBi stands out particularly at low temperatures, while FeNbP and FeNbAs show stable figure-of-merit (<i>ZT</i>) values exceeding 0.74 in the range of 300–800&#xa0;K. These results establish the FeNbX compounds as promising candidates for thermoelectric and optoelectronic applications.</p>

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First-Principles Analysis of the Multifunctional Properties of FeNbX (X = P, As, Bi) Half-Heusler Compounds

  • 期刊论文

  • 发表日期：

    2026年6月1日

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  • Sid Ahmed Bendehiba,
  • Besbes Anissa,
  • Djelti Radouan,
  • Lakhdar Benahmedi,
  • Aissani Ali

摘要

We conducted a comprehensive first-principles investigation of the structural, electronic, mechanical, optical, and thermoelectric properties of FeNbX (X = P, As, Bi) half-Heusler compounds using density functional theory. The structural optimizations showed that all the compounds are more stable in the Type-1 atomic arrangement, with a non-magnetic ground state. They also have negative formation energies, which confirms their thermodynamic stability. The lattice constants increase systematically from FeNbP to FeNbBi, in line with the increasing atomic radii of the X elements. Electronic band structure analysis using the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential indicates indirect bandgaps ranging from 0.62 eV to 0.79 eV, with FeNbBi having the largest gap due to relativistic effects. Density of states analysis highlights that the Fe-d and Nb-d orbitals dominate the states near the Fermi level, while the X-p orbitals contribute significantly depending on the mass of the X atom. Phonon dispersion calculations confirm the dynamic stability of the three compounds. Furthermore, mechanical analysis based on elastic constants attests to their mechanical robustness and moderate ductility. Optical studies reveal high static dielectric constants, strong absorption in the visible and ultraviolet ranges, and enhanced optical response in FeNbBi, particularly in the near-infrared. The assessment of thermoelectric performance, based on Boltzmann transport theory, reveals high Seebeck coefficients. FeNbBi stands out particularly at low temperatures, while FeNbP and FeNbAs show stable figure-of-merit (ZT) values exceeding 0.74 in the range of 300–800 K. These results establish the FeNbX compounds as promising candidates for thermoelectric and optoelectronic applications.