Electrical Properties of Barium and Zirconium Modified NBT Ferroelectric Ceramics

Recently a new wave of interest has risen on relaxor ferroelectrics with complex perovskite structure due to their wide use in fabrication of multilayer ceramic capacitors, electrostrictive actuators, and electromechanical transducers. The polycrystalline 0.93(Bi0.5Na0.5)Ba(0.07)Z(0.04)T(0.96)O(3) (0.07BNBZT) ceramic material, which is in the vicinity of the morphotropic phase boundary (MPB) has been prepared by using high temperature solid state reaction method. The tolerance factor has been estimated and found to be 0.815. XRD analysis revealed a rhombohedral perovskite type structure. SEM micrographs showed highly dense grains with rectangular shape. The average grain size is found to be 1.51 mu m. Dielectric studies in the material ha indicated relaxor behaviour with diffuse phase transition. High value of em >1958 is found at 1kHz, Tm (phase transition temperature) 335 degrees C, The diffuseness parameter was established to be 1.60 revealing the relaxor behaviour. Further, to confirm the relaxor behaviour in the material, Vogel-Fulcher (V-F) relation has been used. Estimated V-F parameters are found to be T-f = 138 degrees C, E-a=0.080eV and v(o) = 2.32x10(8) Hz. Cole-Cole analysis has shown a non-Debye type relaxation in the system. Conductivity studies in the material obeyed the Jonscher's power law in frequency range of (45Hz - 5MHz) and temperature range of (35 degrees C-600 degrees C). The electric conduction in the system may be due to hopping/mobility/transportation of charge carriers.