Ferroelectric domains in the uniaxial relaxor system SBN : Ce, Cr and Co

Abstract

Disordered solid solutions of Sr0.61Ba0.39Nb2O6:X (SBN61:X), where x = Ce3+, Cr3+ or Co2+, undergo a ferroelectric-to-relaxor phase transition when heating to above T-c = 360 K. This is evidenced by monitoring polar 180degrees domains by piezoelectric force microscopy (PFM). Their walls exhibit roughening due to interaction with quenched random electric fields owing to charge disorder, which is strongly enhanced by X = Ce3+ on Sr2+, but less affected by Cr3+ on Nb5+ sites. This is corroborated by crossover of the critical exponents gamma and v from pure to random-field Ising model behavior within the framework of an Ornstein-Zemike-type analysis of linear birefringence data.