Compositionally induced ferroelectric-relaxor crossover in Ba(Zr,Ti)O3 ceramics

Ba(ZrxTi1-x)O3 ceramics with various compositions x =0, 0.10, 0.15 and 0.18 have been prepared by solid state reaction using nanometric precursors of BaCO3, TiO2, and ZrO2. The processing parameters were optimized to obtain pure perovskite phase and homogeneous microstructures and densities higher than 90% for all the samples. The dielectric data showed a ferroelectric-relaxor crossover and a shift of the Curie temperature towards lower values with increasing x. Using the modified Landau model for relaxors, the local order parameter as a function of temperature has been calculated. It was demonstrated that the relaxor character is more evident with increasing the Zr addition. The values obtained by fits with empirical equations of the dielectric data indicated a mixed ferroelectric-relaxor character for all the compositions and an increasing relaxor character with Zr addition.