Advances in dielectric performance of atomically engineered Sr1.8Bi0.2Nb3O10 perovskite nanosheet thin films

The search for new high-performance dielectric materials has attracted considerable research interest. Several mechanisms to achieve high permittivity have been proposed, such as BaTiO3-based perovskites or CaCu3Ti4O12. However, developing high-performance thin films remains a challenge. Here, we propose a new material design route to achieve high permittivity behavior in atomically thin films. We present a concrete example of Dion–Jacobson-type KSr2-xBixNb3O10 and its cation-exchanged form HSr2-xBixNb3O10, which exhibits a stable colossal permittivity and low dielectric loss. In addition, Sr2(1−x)Bi2xNb3O10-δ nanosheets were obtained by chemical exfoliation, with a high dielectric permittivity of over 500—the highest among all known dielectrics in ultrathin films (<20 nm). The Bi substitution of Sr2Nb3O10 led to a two-fold increase in the dielectric permittivity owing to the higher polarizability of Bi ions. Our proposed method provides a strategy for obtaining new high-k nanoscale dielectrics for use in nanoscaled electronics.