THE DIELECTRIC-RELAXATION BEHAVIORS OF (SR0.6BA0.4)(1-2Y)(LI,DY)YNB(2)O(6)

In order to study the effect caused by atomic substitution on the phas e transition in strontium barium niobate of tungsten bronze crystal st ructure, crystallographic and dielectric properties of charge balanced (Sr0.6Ba0.4)(1-2y) (Li,Dy)(y)Nb2O6 ceramic system have been investiga ted for y=0.03, 0.65, 0.68, as a function of temperature and applied f requency. This system reveals two distinct dielectric relaxations in d ifferent temperature ranges. By analyzing the frequency dependence of two dielectric maximum, it was found that our oxide alloy undergo glas sy transition. Moreover, both the broadness and the dielectric maximum temperature of two relaxations are greatly affected by the contents o f substitution cations, implying that lattice strain caused by substit uting of small size cations affects the relaxation phenomena. The diel ectric susceptibility behavior of the high temperature relaxation is d escribed in terms of a wide distribution of relaxation times character izing the interactions of dipolar clusters. The relaxations in low tem perature region are controlled by microdomain type dynamics, which are related to transition from a relaxer ferroelectric to another type fe rroelectric. We also have investigated the structure change, which mig ht be related with dielectric relaxation.