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: Sr_{0.70}Ba_{0.30}Nb_{2}O_{6} (SBN:70 - relaxor) and Sr_{0.26}Ba_{0.74}Nb_{2}O_{6} (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.
Highlights
Strontium-barium niobates, SBN (Srx Ba1−x Nb2O6, 0.25 x 0.75), are ferroelectric crystals that have received a great interest in their applications in optoelectronics [1]
It is interesting to note that the domain switching process in SBN:70 single crystals is similar to that observed in Ni doped SNB:61 single crystals [13]
The domain switching in SBN:26 crystal in the high-field regime may qualitatively resemble the switching observed in classical ferroelectric crystals, in which the growth of the existing domains is more favourable than the creation of new ones due to a relatively low domain-wall energy [25]
Summary
Strontium-barium niobates, SBN (Srx Ba1−x Nb2O6, 0.25 x 0.75), are ferroelectric crystals that have received a great interest in their applications in optoelectronics [1]. The controlled manipulation of the domain structure via external electric field involves an important issue of potential applications, such as optical-frequency conversion and high density optical data storage [2]. Efforts are directed towards producing SBN crystals with high quality ferroelectric domain reversible structures. A few works focusing on SBN domain structure dynamics can be found in literature. The microscale domain structure kinetics in SBN: was investigated using an electro-optic imaging microscope [9, 10] and NLC method [11,12,13]. The observed specific features of the switching process were accounted for freezing or pinning domain walls connected with disordered structure of SBN crystals
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