Ferroelectric domain walls in BaTiO3:: Structural wall model interpreting fingerprints in XRPD diagrams

Accurate analyses of X-ray diffraction patterns of micrometric BaTiO3 grains has shown that 90 degrees domain wall is not a single twin (101) plane but a few nanometers wide region where the twinning crystallographic discontinuity could be accommodated by atom plane translations. A structural model of the 90 degrees domain wall based on curved (001) and (100) planes is proposed. Its theoretical diffraction treatment is developed. The good agreement between experimental fingerprints and theoretical line profiles allows to propose a wall thickness of around 140 Angstrom for micrometric BaTiO3 grains whereas their domain thickness is of the order of 0.1 mu m.