Piezoelectricity in perovskite-type pseudo-cubic ferroelectrics by partial ordering of off-centered cations

• Published in: Communications materials Vol. 1; no. 1; pp. 1 - 8
• Main Authors: Kuroiwa, Yoshihiro, Kim, Sangwook, Fujii, Ichiro, Ueno, Shintaro, Nakahira, Yuki, Moriyoshi, Chikako, Sato, Yukio, Wada, Satoshi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.10.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/996; 639/766/119/1002; 639/766/119/2795; Ceramics; Chemistry and Materials Science; Electric fields; Ferroelectric domains; Ferroelectric materials; Ferroelectricity; Lead free; Materials Science; Perovskites; Phase transitions; Piezoelectricity; Room temperature; Symmetry; Synchrotron radiation; Synchrotrons
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-020-00072-4

A large piezoelectric response in ferroelectric ceramics is typically associated with extrinsic contributions from ferroelectric domain structures. However, such domain structures cannot be expected in systems with pseudo-cubic symmetry. In this study, we determine the mechanism of significant piezoelectricity and ferroelectricity in 0.3BaTiO 3 –0.1Bi(Mg 1/2 Ti 1/2 )O 3 –0.6BiFeO 3 ceramic with a perovskite-type pseudo-cubic symmetry. Synchrotron radiation X-ray diffraction reveals that the Bi ions in this ceramic essentially prefer to be off-centered at six sites by approximately 0.4 Å, in the cubic directions. A phase transition occurs at T C ~725 K. However, the crystal seems to present a cubic symmetry even at room temperature. The large piezoelectric response is caused by the combinational partial ordering of the off-centered Bi ions, adapted to any direction of the applied electric field to the ceramic grains. The proposed mechanism for the emergence of a high polarization in the above system will enable designing novel Pb-free ceramics by controlling the fluctuated and off-centered ions under an applied electric field. Strong piezoelectricity is typically due to reorientation of ferroelectric domains and is not expected in cubic systems. Here, the strong piezoelectricity of pseudo-cubic 0.3BaTiO 3 –0.1Bi(Mg 1/2 Ti 1/2 )O 3 –0.6BiFeO 3 is explained in terms of partial ordering of Bi ions adapted to any applied field direction.