Origin of ferroelectric polarization in bismuth sodium titanate

Noguchi, Yuji*; Aso, Seiyu*; Oyama, Kenji*; Ishigaki, Toru*; Yoneda, Yasuhiro   ; Matsuo, Hiroki*

We explore the electronic structure of high-quality bismuth sodium titanate (BiNaTiO) powders through a comprehensive approach combining the maximum entropy method (MEM)/Rietveld analysis of synchrotron radiation X-ray diffraction data collected at 200 K with density functional theory (DFT) calculations. We conclude that the covalent Bi-O bond and the resultant ferroelectricity stem primarily from the Bi-6p-O3-2p orbital interaction mediated through Ti-3d.