Impact of perovskite layer stacking on dielectric responses in KCa2Nan-3NbnO3n+1 (n=3–6) Dion–Jacobson homologous series.

The dielectric properties of KCa₂Na_n-3Nb_nO_3n+1 (n=3–6) Dion–Jacobson homologous series have been investigated. The dielectric constants ([variant_greek_epsilon]) increase with the number of octahedral units (n), and the n=6 compound (KCa₂Na₃Nb₆O₁₉) exhibits a stable dielectric response with [variant_greek_epsilon]=∼500 between 1 kHz and 1 MHz. This n-dependent behavior is similar to those observed in other layered perovskites such as Ruddlesden–Popper and Aurivillius phases. Raman scattering studies reveal that increase in n in KCa₂Na_n-3Nb_nO_3n+1 leads to higher polarizability of the lattice and softening of the lowest-frequency phonon mode, which is responsible for the observed enhancement in [variant_greek_epsilon] with n. [ABSTRACT FROM AUTHOR]