Triclinic and monoclinic structures of SrLaCuNbO6and SrLaCuTaO6double perovskites

SrLaCuNbO6and SrLaCuTaO6are Jahn–Teller distorted double perovskites with completeB-site ordering. The crystal structure of SrLaCuTaO6has been solved by refinement of neutron powder diffraction data at 323 (triclinic), 573 (monoclinic) and 923 K (body-centered monoclinic). Synchrotron X-ray and electron diffraction reveal local-scale features similar to those seen in ferroelectric perovskites, and also inA-site ordered perovskites exhibiting nanoscale periodicities. The crystal structure of SrLaCuNbO6was solved by refinement of synchrotron X-ray powder diffraction data at 673 and 1273 K. Because of the high resolution of the synchrotron, adjustments to these structure models were necessary in order to account for profile irregularities resulting from the local-scale behavior.

A Review of Domain Modelling and Domain Imaging Techniques in Ferroelectric Crystals

The present paper reviews models of domain structure in ferroelectric crystals, thin films and bulk materials. Common crystal structures in ferroelectric materials are described and the theory of compatible domain patterns is introduced. Applications to multi-rank laminates are presented. Alternative models employing phase-field and related techniques are reviewed. The paper then presents methods of observing ferroelectric domain structure, including optical, polarized light, scanning electron microscopy, X-ray and neutron diffraction, atomic force microscopy and piezo-force microscopy. Use of more than one technique for unambiguous identification of the domain structure is also described.

Atomic-scale study of electric dipoles near charged and uncharged domain walls in ferroelectric films

Ferroelectrics are materials exhibiting spontaneous electric polarization due to dipoles formed by displacements of charged ions inside the crystal unit cell. Their exceptional properties are exploited in a variety of microelectronic applications. As ferroelectricity is strongly influenced by surfaces, interfaces and domain boundaries, there is great interest in exploring how the local atomic structure affects the electric properties. Here, using the negative spherical-aberration imaging technique in an aberration-corrected transmission electron microscope, we investigate the cation-oxygen dipoles near 180 degrees domain walls in epitaxial PbZr(0.2)Ti(0.8)O(3) thin films on the atomic scale. The width and dipole distortion across a transversal wall and a longitudinal wall are measured, and on this basis the local polarization is calculated. For the first time, a large difference in atomic details between charged and uncharged domain walls is reported.

Microstructure of ferroelectric domains in BaTiO3 observed via x-ray microdiffraction

X-ray microdiffraction utilizing Fresnel zone plate focusing optics has been used to study microstructural properties of individual 90 degree ferroelectric domains in BaTiO3. Diffraction measurements at a microfocused spot resolution of 0.3 microm over domain widths of approximately 10 microm unambiguously reveal features of lattice buckling, rotation, and strain near domain boundaries. Our results may be understood within the context of bound residual strain due to lattice mismatch and elastic interactions between neighboring domains.