Modeling the Dielectric Response and Relaxation Spectra of Relaxor Ferroelectrics

A multi‐Debye relaxation model that is based upon the Boltzmann superposition principle has been used to determine the frequency‐dispersion behavior of Pb(Mg 1/3 ‐Nb 2/3 )O 3 (PMN) and Pb 0.88 La 0.08 (Zr 0.65 Ti 0.35 )O 3 (PLZT 8/65/35) relaxor ferroelectrics. For PMN, relaxation times on the order of seconds contribute to the dispersive character of the dielectric properties. A defect‐relaxation mechanism that involves Mg cation hopping in a structure that is composed of interpenetrating 〈111〉 chains of ordered Pb(Mg 1/2 Nb 1/2 )O 3 is proposed for PMN. Motion of the Mg cations results in destruction and reconstruction of these ordered chains, which contributes to the dispersive character of PMN.