Dielectric non-Debye domain wall response and aging of SBN : Ce

Abstract

Different non-Debye dielectric spectra are observed in different low-frequency regimes in a polydomain relaxor ferroelectric single crystal, Sr-0.603 Ce-0.007 Ba-0.39 Nb2O6 ( SBN :Ce), in the vicinity of its transition temperature, T-c approximate to 320 K. At f < 10 Hz the response is due to irreversible creeplike wall motion, chi' proportional to chi'' proportional to omega -beta with beta approximate to 0.2, while polydispersive reversible wall segment relaxation with pink noise character [Joffe and Vinokur, 1987] is encountered at larger frequencies, f > 10 Hz. The crossover between both kinds of dielectric response is attributed to a dynamical phase transition [Nattermann et al. 2001]. While nearly ideal creep is observed in as-cooled samples, deviations towards reversible very-low frequency relaxation are revealed after aging.