Polar nano regions in lead free (Na0.5Bi0.5)TiO3-SrTiO3-BaTiO3 relaxors: An impedance spectroscopic study

Lead free ternary (0.8 - x) Na0.5Bi0.5TiO3-0.2SrTiO(3)-xBaTiO(3) (NBT-ST-BT) relaxor ferroelectric ceramics with dense morphology were investigated by impedance spectroscopy over a wide temperature range from 50 to 400 degrees C. The grain and grain boundary response as well as the relaxation processes at different frequencies and temperatures were discussed using different formalisms. The relaxation time extracted from Z(f) and M(f) spectra for x = 0.04, 0.06, 0.08 follows the Arrhenius law and reveals the existence of three different relaxation processes with different activation energies. The shoulder response in M(f) provides an indirect evidence of the presence of highly polarisable entities in the samples which is a signature of the existence of polar nano regions (PNRs) within the grains. (C) 2017 Elsevier B. V. All rights reserved.