Strain phase diagram and physical properties of (110)-oriented PbTiO3 thin films by phase-field simulations

Abstract

Extensive studies have shown that (110)-oriented ferroelectric films exhibit unique structures and excellent physical properties compared with (001)-oriented ferroelectric films. Showing how the domain structure evolve as the function of epitaxial strain, or establishing a strain phase diagram, should provide valuable information for the controlling of domain structures. In this work, three-dimensional phase-field simulations were performed to investigate the phase (domain) structures and physical properties in (110)-oriented PbTiO3 thin films. We constructed the temperature-misfit strain phase diagram of (110)-oriented PbTiO3 thin films. Typical phase (domain) structures were analyzed in detail and various types of topological flux-closure domains were found to exist in mixed phases. The experimental results on a special substrate KTaO3, in particular the orientation of domain walls, corroborate the simulation results. We found that the misfit strain could be used to engineer the phase (domain) structures and tune the dielectric, piezoelectric and thermal conductivity properties in (110)-oriented PbTiO3 thin films. These results deepen the understanding and provide a theoretical guidance for the strain engineering of the structures and properties of high-index (110)-oriented PbTiO3 thin films.