Substitution effects on the relaxor properties of lead magnesium niobate ceramics

The temperature dependence of the dielectric permittivity is studied in different Pb(Mg1/3Nb2/3)O-3 based ceramics, in which the ordered region size can be changed by introducing titanium or lanthanum ions. Both the relaxer behaviour and the nonlinear dielectric component are found to be dependent on the impurity content. Especially, the nonlinearity increases strongly as the material exhibits a more conventional ferroelectric behaviour, i.e. as the size of the polar clusters, which develop in the paraelectric matrix, increases.