Relaxor ferroelectric behavior and structural aspects of SrNaBi2Nb3O12   ceramics
  SrNaBi2Nb3O12 powder was prepared via the conventional solid-state reaction method. X-ray structural studies confirmed the phase to be a three-layered member of the Aurivillius family of oxides. SrNaBi2Nb3O12 (SNBN) ceramics exhibited the typical characteristics of relaxor ferroelectrics, associated with broad and dispersive dielectric maxima. The variation of temperature of dielectric maxima (Tm) with frequency obeyed the Vogel-Fulcher relationship. Relaxor behavior was believed to be arising from the cationic disorder at A-site. Pinched ferroelectric hysteresis loops were observed well above Tm. 
Sunil Kumar, D. A. Ochoa, J. E. Garcia, and K. B. R. Varma
cond-mat.mtrl-sci