Artificial Solids by Design: Assembly and Electron Microscopy Study of Nanosheet-Derived Heterostructures

Two-dimensional materials do not only attract interest owing to their anisotropic properties and quantum confinement effects but also lend themselves as well-defined building blocks for the rational design of 3D materials with custom-made structures and, hence, properties. Here, we present the bottom-up fabrication of an artificial superlattice derived from positively charged layered double hydroxide (LDH) and negatively charged perovskite layers sequentially assembled by electrostatic layer-by-layer deposition. In contrast to previously employed bulk methods averaging out the elemental distribution within such stacks, we use a combination of HRTEM, STEM, and EEL spectroscopy to elucidate the structure and composition of the multilayer stack with a high spatial resolution on the subnanometer scale. Atomic column resolved STEM coupled with EELS line scans confirms the periodic arrangement of individual nanosheets by evaluation of the Ca-L2,3 and Mn-L2,3 edges. Furthermore, HRTEM confirms the formation of u...