Mechanical exfoliation of non-van der Waals solids: a study of layered perovskite ferroelectric CsPb2Nb3O10

Abstract Mechanical exfoliation of layered materials is one of the most effective methods for obtaining 2D nanosheets. However, this approach is still limited to van der Waals (vdW) layered materials, where interlayer interactions are governed by weak vdW forces. In this study, we used a layered perovskite ferroelectric (CsPb2Nb3O10) as a model system to explore the mechanical exfoliation behavior of ionically bonded non-vdW layered materials. Due to the relatively weak out-of-plane bonds involving the interlayer Cs⁺ ions, CsPb2Nb3O10 could be cleaved into ultrathin sheets with thicknesses ranging from 7.5 to 50 nm. Using piezoresponse force microscopy, we investigated the thickness-dependent ferroelectric properties of CsPb2Nb3O10 nanosheets.