Structural and Electrical Characterization of Ferroelectric SrBi₂Nb₂O₉ Single Crystals Grown by High-Temperature Self-Flux Solution

Abstract

High-quality SrBi₂Nb₂O₉ (SBN) single crystals were grown from a melt using a high-temperature self-flux solution method and Bi₂O₃ added with B₂O₃ as a flux. A suitable thermal profile involving slow cooling rates allowed growing large and translucent SBN crystals exhibiting platelet morphology with typical size ∼5 × 5 mm ² and thickness approximately 400 μm. X-ray diffraction revealed a dominant (001)-orientation of the major face of the platelet crystals and edges oriented parallel to the [110] directions. The dielectric properties were evaluated along the ab-plane and in the c-axis direction. The ferro-paraelectric phase transition was observed at T _C = 440°C with Curie-Weiss relationship above T _C . The anisotropy of dielectric permittivity, i.e., the ratio between permittivity in the ab-plane and along c-axis was about 10 at T _C . The obtained results are used to discuss the observed correlations between anisotropy, crystalline orientation, and electrical properties.

Keywords:

• Bi-layer structured ferroelectrics
• SrBi₂Nb₂O₉ single crystals
• high-temperature self-flux solution growth
• dielectric anisotropy

PACS:

• 81.10.Dn
• 77.84.Dy
• 77.22.Ch
• 77.80.Bh

Acknowledgments

H. Amorín acknowledges the Foundation for Science and Technology (FCT, Portugal) for the financial support through a PhD grant. The authors also thank Dr. Igor K. Bdikin for his technical support and helpful discussion of the x-ray topography measurements.