Electronic Structure of SrBi₂Ta₂O₉ Powders

Abstract

X-ray diffraction, Raman scattering, and X-ray photoemission of SrBi2Ta2O9 powder sample (the Curie temperature of 310 °C) synthesized from a precursor solution showed that the crystal structure of the SrBi2Ta2O9 unit cell was preserved from bulk to surface, and the surface had never been covered with metallic Bi and/or Bi2O3. The theoretical valence band spectrum, derived from the density of states by full-potential linearized augmented plane-wave computation and the photoionization cross section, reproduced well the experimental valence band spectrum. The computation revealed that the valence band maximum is dominated by the O p states and that the low-energy part of the conduction band is formed from the Bi p and Ta d states hybridizing with the O p states. In the vicinity of the conduction band minimum, the hybridization between Bi p states and Ta d states is weak and the Bi p states have slightly lower energy than the Ta d states.

Preparation and photophysical properties of some oxides in Ca–Bi–O system

“…The electronic structures of some Bi contained oxides are also examined in order to understand the relationship between the optical properties and the crystal structures more deeply. The electronic structures of ␣-Bi 2 O 3 and SrBi 2 Ta 2 O 9 have been reported by Carlsson et al [16] and Shimizu et al [17]. In their results, the valence band was consisted of the O-2p orbit and the conduction band was consisted of the Bi-6p orbit.…”

Preparation of a Blue Luminescent Nanosheet Derived from Layered Perovskite Bi2SrTa2O9

“…The conduction band minimum of BST is formed from the Bi 6p and Ta 5d states, and the Bi 6p state has lower energy than the Ta 5d state has. 10 Therefore, the excitation peak at around 340 nm may be assigned to the excitation from the O 2p state to Bi 6p state. The excitation peak at around 300 nm was observed in the excitation spectra of all samples.…”

“…The valence band maximum of BST is dominated by the O 2p states. The conduction band minimum of BST is formed from the Bi 6p and Ta 5d states, and the Bi 6p state has lower energy than the Ta 5d state has …”

Defective [Bi2O2]2+ Layers Exhibiting Ultrabroad Near‐Infrared Luminescence

“…Because Bi 2− x SrTa 2 O 9− y has a virtually identical PL to that of Bi 2.14 Sr 0.75 Ta 2 O 9− x (Figure S9 in the Supporting Information), we next calculated the band structure and the density of states (DOS) of Bi 2− x SrTa 2 O 9− y because of the computational cost to clarify the influence of defects on its electronic structure. The calculated band gap of pristine Bi 2 SrTa 2 O 9 is 2.6 eV (Figure S10 in the Supporting Information), which is smaller than that obtained experimentally . Notably, the valence band maximum (VBM) is mainly composed of O 2 p orbitals, whereas the conduction band minimum (CBM) consists mostly of Ta 5 d orbitals.…”

“…The calculated band gap of pristine Bi 2 SrTa 2 O 9 is 2.6 eV ( Figure S10 in the Supporting Information), which is smallert han that obtained experimentally. [32] Notably,t he valenceb and maximum (VBM) is mainly composed of O2po rbitals, whereas the conductionb and minimum (CBM) consists mostly of Ta 5d orbitals. V O3 was confirmed to be the most stable oxygen vacancy by calculating the formation energies of the five systems containing oxygen vacancies ( Table S2 in the Supporting Information);t his is consistent with experimental results.…”