Correlation between Ferroelectricity and Grain Structures of Face-to-Face Annealed Strontium Bismuth Tantalate Thin Films

Abstract

The correlation between ferroelectricity and grain structures of sol-gel-derived strontium bismuth tantalate (SBT) thin films prepared by face-to-face annealing were investigated. In face-to-face annealing, an SBT film is directly placed, with the film side down, on an other SBT film during the crystallization process. The remanent polarization value of a face-to-face-annealed SBT film was 21 µC/cm2 at an annealing temperature of 750°C, while it was 7 µC/cm2 in the film prepared without face-to-face annealing. It was found from cross-sectional transmission electron microscope images that the SBT films prepared by face-to-face annealing were composed of dense, and of uniform layers corresponding to the annealing cycles, while the films prepared without face-to-face annealing were composed of randomly packed irregular grains. These results suggest that the improvement in ferroelectricity of the face-to-face annealed SBT films is due to the formation of dense, uniform layers.