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

Abstract

Disordered solid solutions of Sr_0.61Ba_0.39Nb₂O₆: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 180° 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 γ and v from pure to random-field Ising model behavior within the framework of an Ornstein-Zernike-type analysis of linear birefringence data.

Key Words:

• Relaxor
• ferroelectric domains
• random-field Ising model
• scanning probe microscopy
• linear birefringence