Advances in dielectric performance of atomically engineered Sr_1.8Bi_0.2Nb₃O₁₀ 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 KSr_2-xBi_xNb₃O₁₀ and its cation-exchanged form HSr_2-xBi_xNb₃O₁₀, which exhibits a stable colossal permittivity and low dielectric loss. In addition, Sr_2(1−x)Bi_2xNb₃O_10-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.