Enhanced polarization and abnormal flexural deformation in bent freestanding perovskite oxides

• Published in: Nature communications Vol. 13; no. 1; p. 5116
• Main Authors: Cai, Songhua, Lun, Yingzhuo, Ji, Dianxiang, Lv, Peng, Han, Lu, Guo, Changqing, Zang, Yipeng, Gao, Si, Wei, Yifan, Gu, Min, Zhang, Chunchen, Gu, Zhengbin, Wang, Xueyun, Addiego, Christopher, Fang, Daining, Nie, Yuefeng, Hong, Jiawang, Wang, Peng, Pan, Xiaoqing
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31-08-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 147/137; 639/301/119/996; 639/925/357/537; Applied physics; Deformation; Ferroelectric materials; Ferroelectricity; Humanities and Social Sciences; Laboratories; Mechanical properties; Membranes; multidisciplinary; Nanoelectromechanical systems; Oxides; Perovskites; Piezoelectricity; Polarization; Science; Science (multidisciplinary); Shrinkage; Values
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32519-2

Recent realizations of ultrathin freestanding perovskite oxides offer a unique platform to probe novel properties in two-dimensional oxides. Here, we observe a giant flexoelectric response in freestanding BiFeO
3
and SrTiO
3
in their bent state arising from strain gradients up to 3.5 × 10
7
 m
−1
, suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO
3
, which implies an unusual bending-expansion/shrinkage effect in the ferroelectric membrane that has never been seen before in crystalline materials. Our theoretical model reveals that this unprecedented flexural deformation within the membrane is attributable to a flexoelectricity–piezoelectricity interplay. The finding unveils intriguing nanoscale electromechanical properties and provides guidance for their practical applications in flexible nanoelectromechanical systems.
Freestanding perovskite oxides pave the way to novel flexural properties. Here, the authors observe the nanoscale strain gradient induced flexoelectric polarization with an unusual flexo-expansion/shrinkage effect in freestanding ferroelectric oxide.