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 BaTiO 3 and PbTiO 3 ) are an important target for 2D ferroelectrics, controlled synthesis of 2D nanosheets still remains a challenge. Here, this issue is addressed by using a new chemical protocol; unilamellar Ti 0.87 O 2 nanosheets can serve as templates, guiding the solvothermal synthesis of 2D BaTiO 3 nanosheets with a molecularly thin thickness (< 3 nm). Raman spectroscopy, second‐harmonic generation, and transmission electron microscopy characterizations suggest the formation of tetragonal ferroelectric BaTiO 3 nanosheets. Based on piezoresponse force microscopy, BaTiO 3 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.