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

The dielectric properties of KCa2Nan−3NbnO3n+1 (n=3–6) Dion–Jacobson homologous series have been investigated. The dielectric constants (e) increase with the number of octahedral units (n), and the n=6 compound (KCa2Na3Nb6O19) exhibits a stable dielectric response with e=∼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 KCa2Nan−3NbnO3n+1 leads to higher polarizability of the lattice and softening of the lowest-frequency phonon mode, which is responsible for the observed enhancement in e with n.