Topotactic Growth of Free-Standing Two-Dimensional Perovskite Niobates with Low Symmetry Phase

Fei Zhou; Yang Li; Xingqi Liao; Shuren Lin; Haizeng Song; Yin Liu; Fuyi Yang; Shancheng Yan; Zhonghong Lai; Yong Liu; Cheng-Yan Xu; Zhihua Yang; Yudong Huang; Liang Zhen; Jingchuan Zhu; Jie Yao

doi:10.1021/acs.nanolett.1c00918

Topotactic Growth of Free-Standing Two-Dimensional Perovskite Niobates with Low Symmetry Phase

Nano Lett. 2021 Jun 9;21(11):4700-4707. doi: 10.1021/acs.nanolett.1c00918. Epub 2021 May 21.

Authors

Fei Zhou^{1

2

3}, Yang Li¹, Xingqi Liao¹, Shuren Lin², Haizeng Song⁴, Yin Liu², Fuyi Yang², Shancheng Yan⁵, Zhonghong Lai⁶, Yong Liu¹, Cheng-Yan Xu⁷, Zhihua Yang¹, Yudong Huang³, Liang Zhen^{1

7}, Jingchuan Zhu¹, Jie Yao^{2

8

9}

Affiliations

¹ National Key Laboratory for Precision Hot Processing of Metals; School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
² Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States.
³ MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China.
⁴ School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
⁵ School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
⁶ Center of Analysis and Measurement, Harbin Institute of Technology, Harbin 150001, China.
⁷ Sauvage Laboratory for Smart Materials, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
⁸ Tsinghua-Berkeley Shenzhen Institute, University of California, Berkeley, California 94720, United States.
⁹ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.

PMID: 34018750
DOI: 10.1021/acs.nanolett.1c00918

Abstract

Here, we report a novel topotactic method to grow 2D free-standing perovskite using KNbO₃ (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 KNbO₂ 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 (P_s) along [101̅]_pc 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.

Keywords: 2D KN; monoclinic phase; stripe domains; topotactic method.