Direct observation of the ferroelectric polarization in the layered perovskite Bi4Ti3O12

We investigated the crystal structure and ferroelectric domains of Bi4Ti3O12 (BTO) by means of transmission electron microscopy (TEM) and single-crystal X-ray diffractometry. From the extinction rule, we determined that the space group in the ferroelectric phase of BTO is P1a1 rather than B2cb and B...

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Bibliographic Details
Published in:Journal of applied physics 2016-10, Vol.120 (14)
Main Authors: Urushihara, Daisuke, Komabuchi, Mai, Ishizawa, Nobuo, Iwata, Makoto, Fukuda, Koichiro, Asaka, Toru
Format: Article
Language:English
Subjects:
Applied physics
Bismuth titanate
Crystal structure
Ferroelectric domains
Ferroelectric materials
Ferroelectricity
Perovskites
Polarization
Scanning electron microscopy
Scanning transmission electron microscopy
Single crystals
Transmission electron microscopy
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Summary:We investigated the crystal structure and ferroelectric domains of Bi4Ti3O12 (BTO) by means of transmission electron microscopy (TEM) and single-crystal X-ray diffractometry. From the extinction rule, we determined that the space group in the ferroelectric phase of BTO is P1a1 rather than B2cb and B1a1 which have been proposed previously. We successfully refined the crystal structure based on the space group P1a1. The 180° and 90° ferroelectric domain structures were observed by the [001]-zone dark-field TEM imaging. In the 180° domain structure, we determined that one component of the polarization vector is parallel to the a-axis. An annular bright-field scanning transmission electron microscopy (ABF-STEM) was performed for the direct observation of the crystal structures. The ABF-STEM images displayed the contrasts with respect to every atomic position in spite of the highly distorted structure of BTO. We could evaluate the tilting and distortion of the [TiO6] octahedra relatively. Therefore, we directly observed the ferroelectric displacements of Bi and Ti ions.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4961719