Composition induced diffused to relaxor ferroelectric phase transition   in lead-free (1-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 0.40) ferroelectric   ceramics
  (1-x)Li0.12Na0.88NbO3-xBaTiO3 (0 to x to 0.40) ferroelectric ceramics were prepared using conventional ceramics route and their phase transitional behavior is investigated by using dielectric spectroscopy. The temperature-dependent dielectric permittivity epsilon'(T) shows a diffused ferroelectric-paraelectric transition for all compositions. An acceptable and competent characterizing parameter (D) of diffused phase transition (DPT), defined by Uchino et al. [J Am Ceram Soc 2010;93:4011], was measured and validated. Interestingly, a crossover from diffused ferroelectric phase transition (FE-DPT) to relaxor ferroelectric (RFE) transition is found for the composition x greater than equal to 0.225. The FE-DPT is characterized by a frequency-independent temperature of dielectric maxima (Tm), while a RFE is found to have frequency-dependent Tm satisfying Vogel-Fulcher relation. The composition induced crossover is attributed to the dynamics of different PNR size and relaxation times that varies with different BaTiO3 content (x) leading to the appearance of a FE-DPT or RFE. 
Supratim Mitra, Ajit R. Kulkarni
cond-mat.mtrl-sci