Article, First-principles investigation of structural, electronic and optical properties of rhombohedral Na0.5Bi0.5TiO3
First-principles investigation of structural, electronic and optical properties of rhombohedral Na0.5Bi0.5TiO3
DOI:
https://doi.org/10.65273/hhit.jna.2026.2.1.029Keywords:
Na₀.₅Bi₀.₅TiO₃, lead-free ferroelectrics, electronic structure, optical response, first-principle calculationsAbstract
Rhombohedral Na₀.₅Bi₀.₅TiO₃ (NBT) is a representative lead-free ferroelectric, yet a unified microscopic understanding linking bonding, electronic structure, and optical response remains incomplete. In this work, first-principles density functional theory calculations are performed to systematically investigate the structural, electronic, magnetic, and optical properties of pristine rhombohedral NBT. The optimized R3c structure is energetically stable and consistent with experimental data. Electronic structure analysis shows that NBT is a direct band-gap semiconductor with a calculated gap of ~2.86 eV, where the valence band is dominated by O-2p states and the conduction band mainly originates from Ti-3d states with minor Bi-6p contributions. Mulliken population analysis reveals a mixed ionic–covalent bonding nature, with pronounced Ti–O covalency. Importantly, a clear correlation between Ti–O covalent interactions, conduction-band formation, and dominant ultraviolet optical transitions is established, providing a quantitative microscopic interpretation beyond previous qualitative studies. Spin-polarized calculations confirm an intrinsically non-magnetic ground state. These results offer a reliable theoretical reference for NBT-based functional materials.
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