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<p>First-principles calculations were employed to investigate the structural, electronic, elastic, optical, phonon, and thermoelectric properties of cubic double-perovskite Ba<sub>2</sub>LaXO<sub>6</sub> (X = Bi, Sb). Both compounds crystallize in the stable Fm-3&#xa0;m structure with negative formation energies of − 1.39&#xa0;eV/atom (Ba<sub>2</sub>LaBiO<sub>6</sub>) and − 1.57&#xa0;eV/atom (Ba<sub>2</sub>LaSbO<sub>6</sub>), and exhibit dynamical stability confirmed by phonon dispersions without imaginary frequencies. At ambient conditions, Ba<sub>2</sub>LaBiO<sub>6</sub> shows a semiconducting band gap of ~ 2.6&#xa0;eV, while Ba<sub>2</sub>LaSbO<sub>6</sub> exhibits a wide insulating gap of ~ 5.1&#xa0;eV; pressure reduces these gaps to ~ 0.8&#xa0;eV and ~ 2.2&#xa0;eV at 9 GPa, respectively. Convergence tests using dense k-point meshes (up to 10 000 points) demonstrate the numerical robustness of the electronic structures. Elastic analysis reveals higher stiffness for Ba<sub>2</sub>LaSbO<sub>6</sub>, with bulk moduli of ~ 121 GPa compared to ~ 103 GPa for Ba<sub>2</sub>LaBiO<sub>6</sub>, whereas the latter remains more ductile. Pressure-dependent thermoelectric calculations predict enhanced performance at elevated temperatures, with maximum figure of merit values approaching ZT ≈ 0.98–0.99 under optimal hole concentration and moderate pressure. These results highlight Ba<sub>2</sub>LaXO<sub>6</sub> double perovskites as pressure-tunable and multifunctional materials for optoelectronic and high-temperature thermoelectric applications.</p>

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Engineering band gaps and thermoelectric properties in Ba2LaXO6 (X = Bi, Sb) double perovskites via first-principles calculations

  • 期刊论文

  • 发表日期：

    2026年4月20日

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  • Amir Ullah,
  • M. D. Alshahrani,
  • Salma Alshehri,
  • Ahmed Azzouz-Rached,
  • Nasir Rahman,
  • Mudasser Husain,
  • Vineet Tirth,
  • Ali Algahtani,
  • Hamza Rekab-Djabri,
  • Muawya Elhadi,
  • Akhlaq Hussain

摘要

First-principles calculations were employed to investigate the structural, electronic, elastic, optical, phonon, and thermoelectric properties of cubic double-perovskite Ba2LaXO6 (X = Bi, Sb). Both compounds crystallize in the stable Fm-3 m structure with negative formation energies of − 1.39 eV/atom (Ba2LaBiO6) and − 1.57 eV/atom (Ba2LaSbO6), and exhibit dynamical stability confirmed by phonon dispersions without imaginary frequencies. At ambient conditions, Ba2LaBiO6 shows a semiconducting band gap of ~ 2.6 eV, while Ba2LaSbO6 exhibits a wide insulating gap of ~ 5.1 eV; pressure reduces these gaps to ~ 0.8 eV and ~ 2.2 eV at 9 GPa, respectively. Convergence tests using dense k-point meshes (up to 10 000 points) demonstrate the numerical robustness of the electronic structures. Elastic analysis reveals higher stiffness for Ba2LaSbO6, with bulk moduli of ~ 121 GPa compared to ~ 103 GPa for Ba2LaBiO6, whereas the latter remains more ductile. Pressure-dependent thermoelectric calculations predict enhanced performance at elevated temperatures, with maximum figure of merit values approaching ZT ≈ 0.98–0.99 under optimal hole concentration and moderate pressure. These results highlight Ba2LaXO6 double perovskites as pressure-tunable and multifunctional materials for optoelectronic and high-temperature thermoelectric applications.