Computational Search for Better Thermoelectric Performance in Nickel-Based Half-Heusler Compounds

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Half-Heusler alloys are promising for thermoelectric (TE) applications but require further optimization.
• Current TE conversion efficiencies are insufficient for widespread real-life applications.
• Identifying novel parent compounds is crucial for advancing TE material development.

Purpose of the Study:

• To identify new, high-performance thermoelectric materials within the half-Heusler alloy family.
• To systematically investigate the mechanical, electronic, and transport properties of candidate materials.
• To explore the potential of nickel-based half-Heusler semiconductors for efficient thermoelectricity.

Main Methods:

• Employed a high-throughput search methodology based on first-principles calculations.
• Screened 378 newly proposed half-Heusler alloys.
• Analyzed mechanical stability (elastic constants, phonon spectra), electronic structure (energy gaps), and transport properties (power factors, figure of merit).

Main Results:

• Identified nine nickel-based half-Heusler semiconductors as promising TE candidates.
• Confirmed mechanical and dynamical stability for the selected compounds.
• NiVAl, NiVGa, and NiVIn exhibit favorable electronic structures and high power factors.
• NiVIn demonstrated the highest predicted figure of merit (0.309) and power factor (5.152 mW m⁻¹ K⁻²).

Conclusions:

• Nickel-based half-Heusler alloys, particularly NiVAl, NiVGa, and NiVIn, are excellent candidates for thermoelectric applications.
• NiVIn shows superior thermoelectric performance compared to many existing pristine and doped half-Heusler materials.
• This research provides a foundation for discovering advanced thermoelectric materials in the half-Heusler family.