The dielectric relaxation behaviors of (Sr0.6Ba0.4)(1-2y)(Li,Dy)yNb(2)O(6)

Abstract

In order to study the effect caused by atomic substitution on the phase transition in strontium barium niobate of tungsten bronze crystal structure, crystallographic and dielectric properties of charge balanced (Sr0.6Ba0.4)(1-2y) (Li,Dy)(y)Nb2O6 ceramic system have been investigated for y=0.03, 0.65, 0.68, as a function of temperature and applied frequency. This system reveals two distinct dielectric relaxations in different temperature ranges. By analyzing the frequency dependence of two dielectric maximum, it was found that our oxide alloy undergo glassy transition. Moreover, both the broadness and the dielectric maximum temperature of two relaxations are greatly affected by the contents of substitution cations, implying that lattice strain caused by substituting of small size cations affects the relaxation phenomena. The dielectric susceptibility behavior of the high temperature relaxation is described in terms of a wide distribution of relaxation times characterizing the interactions of dipolar clusters. The relaxations in low temperature region are controlled by microdomain type dynamics, which are related to transition from a relaxer ferroelectric to another type ferroelectric. We also have investigated the structure change, which might be related with dielectric relaxation.