Zhou Fei, Li Yang, Liao Xingqi, Lin Shuren, Song Haizeng, Liu Yin, Yang Fuyi, Yan Shancheng, Lai Zhonghong, Liu Yong, Xu Cheng-Yan, Yang Zhihua, Huang Yudong, Zhen Liang, Zhu Jingchuan, Yao Jie
National Key Laboratory for Precision Hot Processing of Metals; School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States.
Nano Lett. 2021 Jun 9;21(11):4700-4707. doi: 10.1021/acs.nanolett.1c00918. Epub 2021 May 21.
Here, we report a novel topotactic method to grow 2D free-standing perovskite using KNbO (KN) as a model system. Perovskite KN with monoclinic phase, distorted by as large as ∼6 degrees compared with orthorhombic KN, is obtained from 2D KNbO after oxygen-assisted annealing at relatively low temperature (530 °C). Piezoresponse force microscopy (PFM) measurements confirm that the 2D KN sheets show strong spontaneous polarization () along [101̅] direction and a weak in-plane polarization, which is consistent with theoretical predictions. Thickness-dependent stripe domains, with increased surface displacement and PFM phase changes, are observed along the monoclinic tilt direction, indicating the preserved strain in KN induces the variation of nanoscale ferroelectric properties. 2D perovskite KN with low symmetry phase stable at room temperature will provide new opportunities in the exploration of nanoscale information storage devices and better understanding of ferroelectric/ferroelastic phenomena in 2D perovskite oxides.
