Studies on the relaxor behavior of sol-gel derived Ba(Zr x Ti1− x )O3 (0.30≤x≤0.70) thin films

We have studied the relaxor behavior of sol-gel derived Ba(Zr x Ti1− x )O3 (0.30≤ x≤0.70) thin films. The plausible mechanism of the relaxor behavior has been analyzed from the dielectric data and micro-Raman spectra. Substitution of Zr+4 for Ti+4 in BaTiO3 lattice reduces its long-range polarization order yielding a diffused paraelectric to ferroelectric phase transition. The solid solution system is visualized as a mixture of Ti+4 rich polar region and Zr+4 rich regions and with the increase in Zr contents the volume fraction of the polar regions are progressively reduced. At about 25.0 at% Zr contents the polar regions exhibit typical relaxor behavior. The degree of relaxation increases with Zr content and maximizes at 40.0 at% Zr doped film. The frequency dependence of the polar regions follows Vogel-Fulcher relation with a characteristic cooperative freezing at freezing temperature (Tf). Below Tf, a long range polarization ordering was ascertained from the polarization hysteresis measurement.