Dielectric response to low and infra-low frequency in layered ferroelectrics

Abstract

Features of dielectric response to frequencies in the 0.25.1000 Hz range in ceramic samples of BaBi2Nb2O9, Na0,5Bi8.5Ti2Nb4O27, Na0,5Bi8.5Ti2Ta4O27, and K0,5Bi8.5Ti2Nb4O27 compounds are reported. Considerable relaxation of &egr;'(T) and &egr;"(T) maximums has been observed at all frequencies in BaBi2Nb2O9. Na0,5Bi8.5Ti2Nb4O27 and Na0,5Bi8.5Ti2Ta4O27 are characterised by broad maximums on &egr;'(T) at frequencies below 100 Hz and a weak anomaly in K0,5Bi8.5Ti2Nb4O27 at temperatures well below the paraelectric phase transition. Increasing values of &egr;' are observed at low temperatures in compounds containing sodium. The observed features of dielectric response are explained by largescale charge fluctuations in layered ferroelectrics.