Design of dispersion-free dielectrics as engineering perovskite unit cells of KCa₂Li_(n-3)Nb_nO_3n+1 ceramics

Dion–Jacobson-phase perovskites have received continuous attention owing to their impressive properties such as the ability to convert them into a two-dimensional (2D) form. We report a new Dion–Jacobson phase-layered perovskite KCa₂LiNb₄O₁₃ ceramics prepared by a solid-state synthesis method. The KCa₂LiNb₄O₁₃ ceramic exhibited a large dielectric permittivity of 61 at 1 MHz, which is three times higher than that of KCa₂Nb₃O₁₀ (ε_r = 20), owing to an increase in the number of octahedral units (n), which causes considerably high polarization in perovskite lattices. Moreover, as engineering octahedral units by lithium ion addition instead of sodium ions, KCa₂LiNb₄O₁₃ ceramic showed improved and stable dielectric properties over a wide frequency range. Moreover, the exfoliated form of 2D Ca₂LiNb₄O₁₃ nanosheets was successfully synthesized via a two-step cation exchange method.