Dielectric relaxation and relaxor behavior in bilayered perovskites
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Sr(0.5)Ba(0.5)Bi(2)Nb(2)O(9) ferroelectric ceramics exhibit a complex dielectric behavior, showing typical relaxor behavior. The relaxation processes are described by the Cole-Cole model [K. S. Cole and R. H. Cole, J. Chem. Phys. 9, 341 (1941)]. At temperatures below 490 K, the dielectric relaxation is associated to the relaxorlike ferroelectric behavior, resulting from the inhomogeneous distribution of barium due to its preference for the bismuth site. Above that, the interaction between the dipoles, which form the microdomains above the relaxor ferroelectric peak and the electrons, which are due to the ionization of the oxygen vacancies are discussed as the probable origin of the relaxation.