Non-Debye domain-wall-induced dielectric response in Sr0.61-xCexBa0.39Nb2O6 -: art. no. 220101

Two different non-Debye dielectric spectra are observed in a polydomain relaxor-ferroelectric Sr0.61-xBa0.39Nb2O6:Ce-x(3+) single crystal in the vicinity of its transition temperature, T(c)approximate to320 K. At infralow frequencies the susceptibility varies as chi(*)proportional toomega(-beta), betaapproximate to0.2, and is attributed to an irreversible creep-like viscous motion of domain walls, while logarithmic dispersion due to reversible wall relaxation [T. Nattermann, Y. Shapir, and I. Vilfan, Phys. Rev. B 42, 8577 (1990)] occurs at larger omega.