Origin of relaxor behavior in 0.78(Na0.5Bi0.5)TiO3-0.2SrTiO(3)-0.02BaTiO(3) ceramic: An electrical modulus study

Abstract

The relaxation dynamics of the polar nano-regions (PNRs) in the 0.78Na(0.5)Bi(0.5)TiO(3)-0.2SrTiO(3)-0.02BaTiO(3) lead free ternary system over a wide temperature range (50-650 degrees C) is investigated using complex electric modulus formalism. The modulus spectra are analyzed across three characteristic temperatures T-B, T-m, and T-f with a special focus on the evolution of dynamics of PNRs. Portraying high capacitance of shoulder response as compared to the bulk response in M ''(f) spectra shows indirectly the presence of highly polarisable entities that persist even above T-B and below T-f. The activation energies extracted from an Arrhenius fit to the relaxation time of both bulk and shoulder response signify different relaxation mechanisms. Further, the value of the stretched exponent beta and the scaling behavior study of the M ''(f) spectra envisage temperature sensitive dipolar relaxation.