Element-resolved Kikuchi pattern measurements of non-centrosymmetric materials

Centrosymmetric and pseudo-centrosymmetric structures refined as non-centrosymmetric.

The behaviour of the Flack parameter for centrosymmetric and pseudo-centrosymmetric crystal structures based on crystal structures published as being non-centrosymmetric is presented. It is confirmed for centrosymmetric structures that the value obtained for the Flack parameter is critically dependent on the Friedel coverage of the intensity data, approaching 0.5 for a coverage of 100% and stic...

Principles of depth-resolved Kikuchi pattern simulation for electron backscatter diffraction.

This paper presents a tutorial discussion of the principles underlying the depth-dependent Kikuchi pattern formation of backscattered electrons in the scanning electron microscope. To illustrate the connections between various electron diffraction methods, the formation of Kikuchi bands in electron backscatter diffraction in the scanning electron microscope and in transmission electron microsco...

On the entanglement of electrostriction and non-linear piezoelectricity in non-centrosymmetric materials

Element-specific Kikuchi patterns of Rutile.

The kinetic energy of keV electrons backscattered from a rutile (TiO2) surface depends measurably on the mass of the scattering atom. This makes it possible to determine separately the angular distribution of electrons backscattered elastically from either Ti or O. Diffraction effects of these backscattered electrons inside the rutile crystal lead to the formation of Kikuchi patterns. The eleme...

Non-centrosymmetric Na3Nb4As3O19

A new non-centrosymmetric compound, tris-odium tetra-niobium triarsenic nona-deca-oxide, Na(3)Nb(4)As(3)O(19), has been synthesized by a solid-state reaction at 1123 K. The structure consists of AsO(4) tetra-hedra and NbO(6) octa-hedra sharing corners to form a three-dimensional framework containing two types of tunnels running along the c axis, in which the sodium ions are located. Na(+) catio...