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Context <p>Efficient heat removal limits the performance of microelectronics, plasma-facing components, and high-temperature structures. Metals exhibit good thermal conductivity but weaken above approximately 1000&#xa0;K, while ceramics are strong yet brittle. Ultrahigh-temperature M<sub>3</sub>AlB<sub>4</sub> compounds (M = Ti, Zr, Hf) maintain metallic conductivity while displaying unusually low lattice thermal conductivity. The origin of the ultralow <i>κ</i><sub><i>l</i></sub> in Hf<sub>3</sub>AlB<sub>4</sub> was previously unknown, hindering the design of derivatives with even lower <i>κ</i><sub><i>l</i></sub>. First-principles simulations reveal that the heavy Hf atom doubles the Grüneisen parameter (<i>γ</i> ≈ twice that of Ti<sub>3</sub>AlB<sub>4</sub>), which shortens phonon lifetimes and triples the three-phonon scattering phase space, offsetting the velocity increase from softened Hf-B bonds. By combining direction-resolved lattice thermal conductivity and estimated electronic contributions, the calculated total thermal conductivity of M<sub>3</sub>AlB<sub>4</sub> ranges from 0.76 to 40.6 W/(m·K), enabling composition-tunable thermal management from thermal insulation to heat conduction applications. Selective substitution with heavy atoms thus tunes <i>κ</i><sub><i>l</i></sub> by an order of magnitude without compromising metallic transport, providing a superior platform for thermal barrier coatings, heat spreaders, and thermoelectric elements at higher temperatures.</p> Methods <p>Density functional theory (DFT) calculations were performed using VASP with a plane-wave energy cutoff of 700&#xa0;eV and a 13 × 13 × 13 Monkhorst–Pack k-point mesh. Structural relaxations were carried out until the energy and force convergence criteria were below 1 × 10<sup>–8</sup>&#xa0;eV and 1 × 10<sup>–7</sup>&#xa0;eV/Å, respectively. Crystal orbital Hamiltonian population (COHP) analysis was performed using the LOBSTER package. Harmonic interatomic force constants (IFCs) were obtained using density functional perturbation theory (DFPT) implemented in VASP-Phonopy on a 2 × 2 × 2 supercell. The Thirdorder utility was employed to compute third-order IFCs. The resulting harmonic and third-order IFCs were then input into ShengBTE to calculate the <i>κ</i><sub><i>l</i></sub>.</p>

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Ab initio study of lattice thermal conductivity in layered borides M3AlB4 (M = Ti, Zr, Hf)

  • 期刊论文

  • 发表日期：

    2026年3月31日

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  • Shengzhao Wang,
  • Jinfan Song

摘要

Context

Efficient heat removal limits the performance of microelectronics, plasma-facing components, and high-temperature structures. Metals exhibit good thermal conductivity but weaken above approximately 1000 K, while ceramics are strong yet brittle. Ultrahigh-temperature M3AlB4 compounds (M = Ti, Zr, Hf) maintain metallic conductivity while displaying unusually low lattice thermal conductivity. The origin of the ultralow κl in Hf3AlB4 was previously unknown, hindering the design of derivatives with even lower κl. First-principles simulations reveal that the heavy Hf atom doubles the Grüneisen parameter (γ ≈ twice that of Ti3AlB4), which shortens phonon lifetimes and triples the three-phonon scattering phase space, offsetting the velocity increase from softened Hf-B bonds. By combining direction-resolved lattice thermal conductivity and estimated electronic contributions, the calculated total thermal conductivity of M3AlB4 ranges from 0.76 to 40.6 W/(m·K), enabling composition-tunable thermal management from thermal insulation to heat conduction applications. Selective substitution with heavy atoms thus tunes κl by an order of magnitude without compromising metallic transport, providing a superior platform for thermal barrier coatings, heat spreaders, and thermoelectric elements at higher temperatures.

Methods

Density functional theory (DFT) calculations were performed using VASP with a plane-wave energy cutoff of 700 eV and a 13 × 13 × 13 Monkhorst–Pack k-point mesh. Structural relaxations were carried out until the energy and force convergence criteria were below 1 × 10–8 eV and 1 × 10–7 eV/Å, respectively. Crystal orbital Hamiltonian population (COHP) analysis was performed using the LOBSTER package. Harmonic interatomic force constants (IFCs) were obtained using density functional perturbation theory (DFPT) implemented in VASP-Phonopy on a 2 × 2 × 2 supercell. The Thirdorder utility was employed to compute third-order IFCs. The resulting harmonic and third-order IFCs were then input into ShengBTE to calculate the κl.