Ferroelectric polarization of tetragonal BiFeO3—an approach from DFT calculations for BiFeO3–BaTiO3 superlattices

Density functional theory calculations are conducted for tetragonal BiFeO3–BaTiO3 superlattices to investigate the influence of electronic structures on ferroelectric spontaneous polarization (Ps). When the number of the perovskite unit cells in one layer (N) is decreased below 10, the Ps starts to...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2022-11, Vol.61 (SN), p.SN1002
Main Authors: Noguchi, Yuji, Matsuo, Hiroki
Format: Article
Language:English
Subjects:
Barium titanates
BaTiO
BiFeO
Bismuth ferrite
Covalent bonds
Density functional theory
DFT
Electrons
Ferroelectric materials
Ferroelectricity
ferroelectrics
Mathematical analysis
Perovskites
Polarization
spontaneous polarization
Superlattices
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Summary:Density functional theory calculations are conducted for tetragonal BiFeO3–BaTiO3 superlattices to investigate the influence of electronic structures on ferroelectric spontaneous polarization (Ps). When the number of the perovskite unit cells in one layer (N) is decreased below 10, the Ps starts to decrease from the volume-averaged one (50.9 μC cm−2) and eventually becomes half at N = 1. In the BiFeO3 cell (N = ∞) with a large Ps (73.3 μC cm−2), a covalent bond arising from a Bi_6p-O_2p orbital interaction is extended through a Bi–O network and stereo-chemical lone-pair electrons of Bi are accommodated in the opposite direction of the polar c axis. In the superlattice with N = 1, the Bi–O network cannot be developed by the presence of Ba, and then the Bi–O bond becomes ionic. We show that the large Ps of the BiFeO3 cell originates from the Bi_6p-O_2p mixing superimposed on the stereo-chemical nature of the lone-pair electrons of Bi.
ISSN:0021-4922
1347-4065
DOI:10.35848/1347-4065/ac7bd2