Structural characterization of the low-temperature phase in Sr–Bi–Ta–O films

Abstract

The crystal structure and microstructural evolution of Sr–Bi–Ta–O films grown on LaAlO3 substrates were investigated using x-ray diffraction and cross-sectional transmission electron microscopy. It was found that the epitaxial low-temperature phase found in the as-deposited and 650 °C heat-treated films has a fluorite structure (CaF2-type structure) with a face-centered-cubic symmetry. From the electron diffraction patterns for the fluorite phase, {121212} and {100}-type superlattice spots were observed. The epitaxial fluorite phase was gradually encroached upon by polycrystalline layered perovskite SrBi2Ta2O9 grains during heat treatment at 750 °C.