Phase Transitions and Dynamical Behavior in Ferroelectrics by Molecular-Dynamics Simulation

Simon R. Phillpot
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439

Date:  Thursday, October 2, 2003
Time:  3:30 p.m.
Place:  W183 Nebraska Hall

We show how molecular-dynamics simulation methods are able to reproduce the complex phase behavior of perovskite ferroelectrics. In particular KNbO3 and BaTiO3 each show a sequence of phase transitions from the high-temperature non-ferroelectric cubic phase through tetragonal, orthorhombic and rhombohedral ferroelectric phases. We explore the interaction of these ferroelectric materials with solid solutions and superlattices of related materials, which although non-ferroelectric have a very large dielectric constant. We expose the complex dynamical behavior associated with the phase transitions. Finally we compare the dynamical behavior in perovskites with that of LiNbO3, a ferroelectric material with rather a different crystal structure.

This work was supported by the U. S. Department of Energy, Office of Science under Contract W-31-109-Eng-38.