Study of relaxor behavior in KNN modified NBT-0.2ST ceramic

In this present work, we have studied the glassy and ferroelectric relaxor property of Pb-free 0.72Na0.5Bi0.5TiO3-0.2SrTiO3−0.08K0.5Na0.5NbO3 (0.72NBT-0.2ST-0.08KNN). The single phase 0.72NBT-0.2ST-0.08KNN sample is synthesized using the most conventional solid state reaction route with cubic symmetry. Different empirical formulas like modified Curie-Weiss law (modified CW law), Vogel-Fulcher law, Power law, Lorentz formula, and Cheng's relation are employed to analyze the relaxor characteristics properties further at both lower and higher temperature regions over a wide frequency range. The diffuseness coefficient (γ) t is evaluated from the modified CW law i.e. γ=1.94123 describing the relaxor nature of the material. The strong relaxor nature of the sample is also suggested from the frequency and temperature dependent dielectric curve. Moreover, high and low temperature studies provide a brief idea about the dynamics of small polar nano regions.