Relaxor properties of SBN : Ce

Relaxor properties of Sr0.61-xBa0.39Nb2O6:Ce-x(3+) (SBN61:Ce) are examined by dielectric spectroscopy, linear birefringence (LB) and optical second harmonic generation (SHG) as a function of frequency and temperature before and after poling. Relaxor behavior with large polydispersivity is observed above the ferroelectric phase transition temperature T-c. Below T-c a long-range ordered ferroelectric state with low polydispersivity prevails. An Ornstein-Zenike analysis of LB data suggests that pure SBN61 belongs to the 3D Ising universality class. Doping with Ce3+ ions, which seem to act as random fields, enhances the relaxor properties.