Ferroelectric and dielectric characterization studies on relaxor- and ferroelectric-like strontium-barium niobates

Abstract

Ferroelectric domain structure evolution induced by an external electric field was investigated by means of nematic liquid crystal (NLC) method in two strontium-barium niobate single crystals of nominal composition: Sr0.70Ba0.30Nb2O6 (SBN:70 - relaxor) and Sr0.26Ba0.74Nb2O6 (SBN:26 - ferroelectric). Our results provide evidence that the broad phase transition and frequency dispersion that are exhibited in SBN:70 crystal have a strong link to the configuration of ferroelectric microdomains. The large leakage current revealed in SBN:26 may compensate internal charges acting as pinning centers for domain walls, which gives rise to a less restricted domain growth similar to that observed in classical ferroelectrics. Microscale studies of a switching process in conjunction with electrical measurements allowed us to establish a relationship between local properties of the domain dynamics and macroscopic response i.e., polarization hysteresis loop and dielectric properties.

Keywords

• relaxor ferroelectrics
• niobates
• domain walls
• switching process
• SBN