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<p>This study presents a comprehensive first-principles investigation of the VCoSn half-Heusler compound using density functional theory within the Quantum ESPRESSO framework, employing the Perdew-Burke-Ernzerhof generalized gradient approximation to model electron exchange–correlation effects in its cubic F-43&#xa0;m structure. Structural optimization via the Broyden-Fletcher-Goldfarb-Shanno algorithm yields a lattice constant of approximately 5.9&#xa0;Å, with phonon dispersion confirming dynamical stability by the absence of imaginary frequencies, akin to stable analogs such as TaCoSn. The electronic band structure reveals metallic behavior with no bandgap and a high density of states near the Fermi level, dominated by V and Co d-orbitals, drawing parallels to VFeSb. The complex Fermi surface exhibits anisotropic sheets with nesting features that enhance electron–phonon interactions. Optical properties, including dielectric function and absorption spectra, indicate potential for photonic applications, with strong responses in the visible range. Mechanical analysis uncovers elastic anisotropy, with bulk modulus ~ 140&#xa0;GPa, shear modulus ~ 80&#xa0;GPa, and Young’s modulus ~ 200&#xa0;GPa, confirming ductility (Poisson’s ratio ~ 0.26) and robustness for stress-bearing uses, like HfNiSn. Thermoelectric transport properties, computed via BoltzTraP, show temperature-dependent electrical conductivity peaking at ~ 6 × 10<sup>20</sup> Ω<sup>−1</sup>&#xa0;m<sup>−1</sup>&#xa0;s<sup>−1</sup> at 800&#xa0;K, asymmetric Seebeck coefficients up to ± 8 × 10<sup>–5</sup>&#xa0;V/K indicating n-type dominance, and power factors reaching ~ 1 × 10<sup>12</sup> W/m·K<sup>2</sup> s, alongside electronic thermal conductivity ~ 1 × 10<sup>16</sup> W/m·K. The figure of merit (ZT) reaches a maximum of ~ 0.20 at low temperatures, then diminishes to ~ 0.10 at 800&#xa0;K due to bipolar effects. Yet, low lattice thermal conductivity (~ 1–2&#xa0;W/m·K) suggests promise for mid-temperature energy harvesting. These findings position VCoSn as a tunable material for thermoelectric devices, spintronics, and structural applications, suggesting doping (e.g., Nb) to optimize ZT. Limited experimental synthesis of VCoSn has been reported, yielding a lattice constant of ~ 5.95&#xa0;Å and a low ZT ≈ 0.007, consistent with our computed lattice constant (~ 5.9&#xa0;Å) and metallic character; however, phase purity remains challenging due to competing phases.</p>

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First-principles DFT investigation of structural, electronic, optical, mechanical, and thermoelectric properties of VCoSn half-heusler compound

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Shivani Shah,
  • Karam Chand,
  • Mitesh B. Solanki,
  • Nisha Mahepal

摘要

This study presents a comprehensive first-principles investigation of the VCoSn half-Heusler compound using density functional theory within the Quantum ESPRESSO framework, employing the Perdew-Burke-Ernzerhof generalized gradient approximation to model electron exchange–correlation effects in its cubic F-43 m structure. Structural optimization via the Broyden-Fletcher-Goldfarb-Shanno algorithm yields a lattice constant of approximately 5.9 Å, with phonon dispersion confirming dynamical stability by the absence of imaginary frequencies, akin to stable analogs such as TaCoSn. The electronic band structure reveals metallic behavior with no bandgap and a high density of states near the Fermi level, dominated by V and Co d-orbitals, drawing parallels to VFeSb. The complex Fermi surface exhibits anisotropic sheets with nesting features that enhance electron–phonon interactions. Optical properties, including dielectric function and absorption spectra, indicate potential for photonic applications, with strong responses in the visible range. Mechanical analysis uncovers elastic anisotropy, with bulk modulus ~ 140 GPa, shear modulus ~ 80 GPa, and Young’s modulus ~ 200 GPa, confirming ductility (Poisson’s ratio ~ 0.26) and robustness for stress-bearing uses, like HfNiSn. Thermoelectric transport properties, computed via BoltzTraP, show temperature-dependent electrical conductivity peaking at ~ 6 × 1020 Ω−1 m−1 s−1 at 800 K, asymmetric Seebeck coefficients up to ± 8 × 10–5 V/K indicating n-type dominance, and power factors reaching ~ 1 × 1012 W/m·K2 s, alongside electronic thermal conductivity ~ 1 × 1016 W/m·K. The figure of merit (ZT) reaches a maximum of ~ 0.20 at low temperatures, then diminishes to ~ 0.10 at 800 K due to bipolar effects. Yet, low lattice thermal conductivity (~ 1–2 W/m·K) suggests promise for mid-temperature energy harvesting. These findings position VCoSn as a tunable material for thermoelectric devices, spintronics, and structural applications, suggesting doping (e.g., Nb) to optimize ZT. Limited experimental synthesis of VCoSn has been reported, yielding a lattice constant of ~ 5.95 Å and a low ZT ≈ 0.007, consistent with our computed lattice constant (~ 5.9 Å) and metallic character; however, phase purity remains challenging due to competing phases.