Glassy behavior study of dysprosium doped barium zirconium titanate relaxor ferroelectric

摘要

We report the glassy behavior of dysprosium doped barium zirconium titanate single phase perovskite ceramics with general formula Ba_(1-x)Dy(2x/3)Zr_(0.25)Ti_(0.75)O3 prepared by solid-state reaction method. Temperature and frequency dependent dielectric studies of the ceramics reveal relaxor behavior. A non-Debye relaxation, which is analogous to the magnetic relaxation in spin-glass system, is observed clearly around temperature of dielectric permittivity maximum (T_m). Frequency dependence of T_m governed by production of polar nano-regions is analyzed using Debye relation, Vogel-Fulcher (V-F) relation and power law. A clear change in dynamic behavior is observed by power parameter which is related to growth of interactions between polar nano-regions with different composition. Various parameters like activation energy for relaxation, freezing temperature, relaxation frequency, etc., are determined after non-linear curve fitting. Temperature dependence of dielectric constant at temperatures much higher and lower than T_m is analyzed by two exponential functions, which gives an idea about the production of polar clusters at high temperature and distribution of freezing temperatures at lower temperature. Various other associated parameters are calculated by non-linear curve fitting and their significance has been explained.