Out-of-phase boundaries (OPBs) are translation boundary defects characterized by a misregistry of a fraction of a unit cell dimension in neighboring regions of a crystal. Although rarely observed in the bulk, they are common in epitaxial films of complex crystals due to the physical constraint of the underlying substrate and a low degree of structural rearrangement during growth. OPBs can strongly affect properties, but no extensive studies of them are available. The morphology, structure, and nucleation mechanisms of OPBs in epitaxial films of layered complex oxides are presented with a review of published studies and new work. Morphological trends in two families of layered oxide phases are described. The atomic structure at OPBs is presented. OPBs may be introduced into a film during growth via the primary mechanisms that occur at film nucleation (steric, nucleation layer, a-bmisfit, and inclined-cmisfit) or after growth via the secondary nucleation mechanism (crystallographic shear in response to loss of a volatile component). Mechanism descriptions are accompanied by experimental examples. Alternative methods to the direct imaging of OPBs are also presented.

Ferroelectric domain structures of (001)SrBi 2 Nb 2 O 9 epitaxial films, investigated using both transmission electron microscopy and phase-field simulations, are reported. Experiment and numerical simulation both reveal that the domain structures consist of irregularly shaped domains with curved domain walls. It is shown that the elastic contribution to domain structures can be neglected in SrBi 2 Nb 2 O 9 due to its small ferroelastic distortion, less than 0.0018%. Two-beam dark-field imaging using reflections unique to domains of each of the two 90°polarization axes reveal the domain structure. Phase-field simulation is based on the elastic and electrostatic solutions obtained for thin films under different mechanical and electric boundary conditions. The effects of ferroelastic distortion and dielectric constant on ferroelectric domains are systematically analyzed. It is demonstrated that electrostatic interactions which favor straight domain walls are not sufficient to overcome the domain wall energy which favors curved domains in SrBi 2 Nb 2 O 9 .

The domain structure in a ferroelectric with well-defined crystallography and negligible ferroelastic distortion (<0.002%) is reported. In contrast to prototypical ferroelectrics in which long-range elastic strain dictates the domain structure, in SrBi2Nb2O9 the elastic term is insignificant, allowing dipole-dipole interactions and domain wall energies to dominate in determining the domain structure. Electron microscopy reveals ferroelectric domains that are irregularly shaped and highly curved. Out-of-phase boundary defects are shown to be weakly correlated with 90 degrees ferroelectric domain structure.

Effect of bismuth on the ferroelectric properties of SrBi 2 Ta 2 O 9 thin films deposited on Pt/SiO 2 /Si by a modified radio-frequency magnetron sputtering technique J. Vac. Sci. Technol. A 16, 2505 (1998); 10.1116/1.581373 Sr 0.8 Bi 2.5 Ta 1.2 Nb 0.9 O 9+x ferroelectric thin films prepared by two-target off-axis radio frequency magnetron sputtering ͑103͒ fiber-textured SrBi 2 Nb 2 O 9 thin films have been grown on Pt-coated Si substrates using a SrRuO 3 buffer layer. High-resolution transmission electron microscopy reveals that the fiber texture arises from the local epitaxial growth of ͑111͒ SrRuO 3 grains on ͑111͒ Pt grains and in turn ͑103͒ SrBi 2 Nb 2 O 9 grains on ͑111͒ SrRuO 3 grains. The films exhibit remanent polarization values of 9 C/cm 2 . The uniform grain orientation ͑fiber texture͒ should minimize grain-to-grain variations in the remanent polarization, which is important to continued scaling of ferroelectric memory device structures.

Continuous single c-domain! single crystal thin films of PbTiO3 (PT) , 10 to 300 nm in film thickness, were epitaxially grown on the miscut (OO1)SrTiO3 substrates. The PT thin films were grown under a step-flow growth and their surface was atomically flat. The interface between thin films and the substrates were coherrent. These sputtered PT thin films were tetragonally deformed but the thin films were tightly bonded to the susbstrates. The lattice parameters did not change at the Curie temperature. The PT thin films exhibited modified ferroelectric properties and/or 2nd order like ferro-paraelectric phase transition. The PT thin films exhibited a diffused peak at the Curie temperature of 520°C. The P/E hysteresis curve showed a sharp switching property with a rectangular pattern and a high coercive field of400 to 500 kV/cm.