Discovery of Novel Piezoelectric Materials with Layered Perovskite Structure (Press Release)
- Release Date
- 18 Apr, 2014
- BL02B2 (Powder Diffraction)
Kyoto University
Key points
• Discovery of novel piezoelectric materials (a family of perovskite compounds) with a mechanism different from the conventional one
• Clarification of inversion symmetry in the crystal structure broken by the oxygen octahedral rotations in the layered structure through experiments and theoretical calculations
• Contribution to the research and development of lead-free piezoelectric materials
|
A research group led by Hirofumi Akamatsu (research fellow of Japan Society for the Promotion of Science at that time), Koji Fujita (associate professor), Toshihiro Kuge (master's student), and Katsuhisa Tanaka (professor) of the Graduate School of Engineering, Kyoto University, found that a series of layered compounds with the formula 'NaRTiO4 (R denotes a rare-earth element) exhibit piezoelectricity through a mechanism different from the conventional one, as demonstrated by both experiments and theoretical calculations. The group collaborated with a research group led by Isao Tanaka (professor) of the Graduate School of Engineering, Kyoto University, Atsushi Togo (program-specific associate professor) of the Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Venkatraman Gopalan (professor) and Long-Qing Chen (professor) of Pennsylvania State University, and James M. Rondinelli (associate professor) of Drexel University. Their achievements were published in Physical Review Letters, an academic journal of the American Physical Society, and their paper was selected as one of the Editors' suggestion papers. Publication： |
<<Caption>>
(b) Crystal structure without inversion symmetry found in this study.
The BO6 oxygen octahedral rotations in (a) and (b) are different, and the one in (b) breaks inversion symmetry.
in layered perovskite oxide 'NaRTiO4 (R denotes rare-earth element) polycrystals.
(b) Piezoresponse force microscopy* image of NaHoTiO4 polycrystals at room temperature.
As shown in (a), the inversion symmetry is broken in the temperature range in which SHG is observed. The image in (b) corresponds to the response in the vertical direction (electric-field direction) with respect to the viewing plane.
Peaks at the diffraction angle of 2θ≈9° show the inversion symmetry in the crystal structure broken by oxygen octahedral rotations as shown in (b). At a temperature of 800 K or above, the crystal structure changes to that without oxygen octahedral rotations, as shown in (c). Because this structure has no octahedral rotation, diffraction peaks disappear. Moreover, SHG in NaSmTiO4 is not observed at a temperature of 800 K or above as shown in Fig. 2(a) due to the centrosymmetry. Taken together, oxygen octahedral rotations are closely related to the inversion symmetry breaking.
<<Glossary>>
* Piezoresponse force microscopy
A microscopy method for mapping piezoelectric response through scanning with a voltage applied between the probe and the sample contact area.
|
For more information, please contact: |
- Previous Article
- Electron dynamics in copper oxide superconductors unveiled by three inelastic-scattering techniques (Press Release)
- Current article
- Discovery of a New Crystal Structure Family of Oxide-Ion Conductors NdBaInO4 (Press Release)