Diffraction contrast between inversion domains and at inversion domain boundaries

Abstract

Inversion domains are revealed in dark field images by a difference in background intensity. The inversion boundaries show an α‐like fringe contrast i.e. a symmetrical fringe pattern in bright field and an asymmetrical pattern in the dark field image. Experimental evidence for these contrast features are obtained from the non‐centrosymmetrical α‐GeTe. A theoretical analysis of the contrast characteristics is presented which is based on the logical assumption that for a non‐centro‐symmetrical crystal, the phases of extinction distance and of the absorption length are different. A very good agreement is found between theory and experiment for the contrast between the domains as well as for the fringe patterns at the boundaries. Also a particular multiple beam situation is treated.

Controlled Synthesis and Size-Dependent Polarization Domain Structure of Colloidal Germanium Telluride Nanocrystals

“…Electron diffraction patterns of the 100 nm particles, in contrast, reveal splitting of diffraction spots consistent with the formation of {100} and {110} twin boundaries (Figure ), and scanning electron microscope (SEM) and Z-contrast TEM imaging (SI, Figure S3) show extensive faceting. The change in lattice orientation across {100} and {110} domain boundaries leads to pronounced diffraction contrast in dark-field images . The breakdown of Friedel symmetry for noncentrosymmetric crystals leads to differences in background contrast between inversion domains in dark-field images, and observation using complementary g⃗ and −g⃗ diffraction vectors results in a reversal of the relative contrast .…”

Antiferroelectrics: History, fundamentals, crystal chemistry, crystal structures, size effects, and applications

“…The Zig–Zag walls, under this circumstance, can also minimize the divergence in the polarization. Transmission electron microscopy is a very powerful tool to quantify the domain orientations, and diffraction contrast methods in bright field and dark can be used to determine the walls and the orientational relations between each domain as modeled by Amenlickx and co‐workers 201–203 . Also, electron holography and differential phase imaging allows for the atomic strain and polarizations to be determined 204–209 …”

Structural defects in ZnO thin films grown by atomic layer deposition at low temperatures

“…However, it is not fulfilled for noncentrosymmetric crystals (lack of inversion symmetry), leading up to an opposite contrast that comes from a change of polarity in the sample. In this way, the background contrast is reversed from one domain to another [5]. The hexagonal wurtzite structure has the noncentrosymmetric along the [0001] direction and the reflections g = 0002 and g =000-2 produce the inversion contrast in the regions of the IDs.…”

“…As proof of the I2 SF, the Burgers circuit drawn around the faults does not exhibit any close failure as indicated in Figure 1a. A different case is presented in Figure 1b where an IDB's is separated by a basal SF, resulting in a Shockley partial dislocation [5], in which a reaction between Burgers vectors of the prismatic and basal stacking faults is taking place: 1/6< 20-23 > = 1/3< 10-10 > +1/2< 0001 >. Figure 1c shows the strain map of the interaction between the IDB and the SF using geometrical phase analysis method (GPA) [8].…”