Dielectric relaxation and phase transition behaviors in (1–x)Pb(Zn 1/3 Nb 2/3 )O 3 -xBaTiO 3 (PZN-BT) binary solid
solutions have been systematically studied in this paper. All the compositions display a pure pseudo-cubic
perovskite structure. As the BT contents increase from 10 mol% to 70 mol%, the phase transition peak becomes
broader and broader, accompanying with decreases of ɛ m (the maximum dielectric permittivity) and T m (the
temperature corresponds to the ɛ m ). Nevertheless, an abnormal increase of ɛ m and T m occurs when the BT
contents exceeds 70 mol%, forming a “U” shaped curve of the compositional dependence of ɛ m and T m . Moreover,
it is indicated from the new glass model fitting results that the characteristic parameter p, which represents the
degree of relaxation, also shows a similar “U” shaped variation curve. Similarly, as shown in polarization-electric
field loops, both remnant polarizations (P r ) and coercive fields (E c ) display the “U” shaped curve as the BT
content changes from 10 mol% to 80 mol%. Finally, according to the similar variation of these key parameters
mentioned above, a polarization mismatched model, which describes the destruction and reestablishment of the
long range order arrangement in solid solutions composed of two kinds of ferroelectrics, is proposed to illustrate
the underlying mechanism. In this PZN-BT system or other similar ABO 3 -type perovskite relaxors, the compe-
tition between the A-O and B-O coupling plays an important role to form the “U” shaped evolution of these key
parameters.