Electron Optical Studies of Barium Titanate Single Crystal Films

Delicate balance between ferroelectricity and antiferroelectricity in hexagonal InMnO3

“…However, the same extinction rules in both FE and PUA states provide difficulties to distinguish them from, for example, x-ray structural refinements, even though slightly different intensity ratios of Bragg peaks exist due to different structural factors. On the other hand, dark-field transmission electron microscopy (DF-TEM) is an ideal and well-known technique to examine domain structures in ferroelectric and non-ferroelectric materials because of its high spatial resolution and ability to isolate specific-type domains using a specific diffraction spot 1,13 . In particular, we can examine the existence of inversion symmetry by taking advantage of the Friedel's law, where the Friedelrelated pairs of Bragg reflections should behave differently in a non-centrosymmetric structure 13,14 .…”

“…On the other hand, dark-field transmission electron microscopy (DF-TEM) is an ideal and well-known technique to examine domain structures in ferroelectric and non-ferroelectric materials because of its high spatial resolution and ability to isolate specific-type domains using a specific diffraction spot 1,13 . In particular, we can examine the existence of inversion symmetry by taking advantage of the Friedel's law, where the Friedelrelated pairs of Bragg reflections should behave differently in a non-centrosymmetric structure 13,14 . In this letter, we have investigated the domain morphologies of a series of h-InMnO 3 specimens prepared in different conditions using DF-TEM as well as high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) with atom-resolved spatial resolution.…”

Electron microscope analyses of domains and discommensurations in ferroelectric Rb2ZnCl4

“…For k = 0 as in the present experiments F*F~ is equal to F'F2 and F'F6 by Friedel's law and domain contrast is not expected. Therefore, the observed weak contrast must be due to the failure of Friedel's law as in the case of BaTiO3 (Tanaka & Honjo, 1964) since other possible reasons for the contrast, such as difference in the excitation error between the neighboring domains, do not exist in the present case.…”

Features of the ferroelectric rhombohedral state in Ba(Ti_1&minus;<i>_x</i>Zr<i>_x</i>)O₃ having the simple perovskite structure

“…Then, the point to note here is that, when the scattering and polarization vectors are denoted by g and P, a ferroelectric domain with g·P > 0 can be observed as bright contrast in dark field images. 17), 18) In other words, a contrast between two neighboring domains with P and -P is vanished for the condition of g¦P.…”