The explanation of dielectric BaTiO3 properties using picosecond ion dynamics


BaTiO3 is frequently considered a model ferroelectric material whose dielectric properties are primarily determined by a Ti ion shifts with respect to surrounding oxygen octahedra. In spite of decades of dedicated research, a lot remains to be clarified in this field.  For example, a clear and convincing description of the collective Ti ion dynamics is mising until now. We decided to study this problem using “nanoscopic” X-ray diffraction methods and atomistic simulations; by combining the methods, we have managed to demonstrate that the titanium ion dynamics may exhaustively be described in terms phonons, excited at picosecond timescales.

Displacements in cubic BaTiO3

One component of the relative Ti-O6 displacement is mapped within a layer of the material using different averaging times (a-c). This clearly shows that chain correlations exist on a timescale of picoseconds. The displacements averaged over the simulation time and all unit cells of the crystal have a cuboidal distribution with shallow minima along the body diagonal directions.

Cooperating institutions:

  • Research School of Chemistry, Australian National University, Australia
  • Institut Laue-Langevin, France

Contact person: Marek Paściak