Molecularly Thin BaTiO₃ Nanosheets with Stable Ferroelectric Response

Abstract

2D ferroelectrics provide great promise for future electronics owing to their unique properties at 2D limit. Although simple perovskite oxides(such as BaTiO₃ and PbTiO₃) are an important target for 2D ferroelectrics, controlled synthesis of 2D nanosheets still remain a challenge. Here, thisissue is addressed by using a new chemical protocol; unilamellar Ti<>sub0.87O₂ nanosheets can serve as templates, guiding the solvothermal synthesis of2D BaTiO₃ nanosheets with a molecularly thin thickness (< 3 nm). Raman spectroscopy, second harmonic generation, and transmission electron microscopy characterizations suggest the formation of tetragonal ferroelectric BaTiO3 nanosheets. Based on piezoresponse force microscopy, BaTiO₃ nanosheets exhibit a clear ferroelectric response with a high Curie temperature (≈100 °C) even down to 1.8 nm thickness. This study provides new opportunities to investigate perovskite ferroelectrics with the critical thickness.