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<p>Although the first principles for achieving universal correlations among the structural, electronic, dielectric, thermal, and thermoelectric properties of Barium titanate (BaTiO₃) (subsystem transition from the cubic–tetragonal phase) have been widely studied, such an understanding remains limited. This study fills this gap by conducting a unified density functional theory (DFT) study of BaTiO₃ in its cubic (Pm–3m) and tetragonal (P4mm) phases. Structures and elastic constants were determined that satisfy Born stability criteria and verify the mechanical stability of both phases. Indirect semiconductive behavior in the electronic band structures is observed, yielding band gaps of approximately 2.1&#xa0;eV (cubic) and 2.2&#xa0;eV (tetragonal), representing the second aspect of indirect semiconductivity. The tetragonal phase exhibits pronounced Ti off-centering, a strong spontaneous polarization (~ 26 µC cm⁻²), and a very high static dielectric constant (~ 320) is observed (compared to the cubic phase (~ 180)). Thermal observations reveal phonon softening and anharmonicity increase for the tetragonal phase, as manifested by decreased Debye temperature and higher thermal expansion. Moreover, thermoelectric studies indicate that the thermal conductivity is lower in the tetragonal phase owing to phonon scattering and higher in the cubic phase. Taken together, these results directly link structural distortion, ferroelectricity, transport, and transport potentials, and BaTiO₃ can be considered a multifunctional material for dielectric, ferroelectric, and thermoelectric applications. This has introduced a unified framework for the phase-dependent multifunctionality of perovskite oxides.</p>

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Multifunctional Properties of BaTiO3 Across the Cubic–Tetragonal Phase Transition: Implications for Ferroelectric and Electronic Applications

  • 期刊论文

  • 发表日期：

    2026年6月17日

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  • Abhay P. Srivastava,
  • Pankaj Sharma,
  • Brijesh K. Pandey,
  • Alok Mishra

摘要

Although the first principles for achieving universal correlations among the structural, electronic, dielectric, thermal, and thermoelectric properties of Barium titanate (BaTiO₃) (subsystem transition from the cubic–tetragonal phase) have been widely studied, such an understanding remains limited. This study fills this gap by conducting a unified density functional theory (DFT) study of BaTiO₃ in its cubic (Pm–3m) and tetragonal (P4mm) phases. Structures and elastic constants were determined that satisfy Born stability criteria and verify the mechanical stability of both phases. Indirect semiconductive behavior in the electronic band structures is observed, yielding band gaps of approximately 2.1 eV (cubic) and 2.2 eV (tetragonal), representing the second aspect of indirect semiconductivity. The tetragonal phase exhibits pronounced Ti off-centering, a strong spontaneous polarization (~ 26 µC cm⁻²), and a very high static dielectric constant (~ 320) is observed (compared to the cubic phase (~ 180)). Thermal observations reveal phonon softening and anharmonicity increase for the tetragonal phase, as manifested by decreased Debye temperature and higher thermal expansion. Moreover, thermoelectric studies indicate that the thermal conductivity is lower in the tetragonal phase owing to phonon scattering and higher in the cubic phase. Taken together, these results directly link structural distortion, ferroelectricity, transport, and transport potentials, and BaTiO₃ can be considered a multifunctional material for dielectric, ferroelectric, and thermoelectric applications. This has introduced a unified framework for the phase-dependent multifunctionality of perovskite oxides.