Locating La atoms in epitaxial Bi3.25La0.75Ti3O12 films through atomic resolution electron energy loss spectroscopy mapping

Atomic resolution high-angle annular dark-field imaging of La-doped bismuth titanate (BLT), Bi3.25La0.75Ti3O12, has been carried out with an aberration-corrected transmission electron microscope. The HAADF image revealed the presence of defects in the [Bi2O2]2+ layers and extra atomic rows between the [Bi2O2]2+ layers and the [Bi2Ti3O10]2− perovskite slabs. Electron energy loss spectroscopy elemental mapping at atomic resolution revealed the exact location of La dopants in the bismuth titanate parent unit cell. These results are discussed in terms of large remanent polarization and enhanced fatigue resistance in BLT.