Molecularly Thin BaTiO ₃ 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.