Application of synchrotron-based reciprocal-space mapping at a fixed angular position to identification of crystal symmetry of Bi₄Ti₃O₁₂epitaxial thin films

Abstract

The crystal structures of Bi4Ti3O12 epitaxial films with thicknesses of 50 and 3 nm were investigated using synchrotron‐based diffraction. Films with (100)/(010) orientations (i.e.a and b domains) were grown on TiO2 (101) single crystals using metal–organic chemical vapor deposition. Synchrotron‐based reciprocal‐space mapping at a fixed angular position was applied to the determination of the crystal symmetry of the films. This method used a grazing‐incidence geometry at a fixed azimuthal angle using 25 keV incident X‐rays, which enabled the generation of a reciprocal‐space map with a single X‐ray exposure. The maps recorded about 120 and 30 diffraction spots from the 50 and 3 nm‐thick samples, respectively. A two‐dimensional 200 × 250 mm detector was used 133 mm downstream from the sample. The results revealed that both Bi4Ti3O12 films had a B1a1 monoclinic structure or a lower crystal symmetry.