Crystallography at the nanoscale: planar defects in ZnO nanospikes

Abstract

The examination of anisotropic nanostructures, such as wires, platelets or spikes, inside a transmission electron microscope is normally performed only in plan view. However, intrinsic defects such as growth twin interfaces could occasionally be concealed from direct observation for geometric reasons, leading to superposition. This article presents the shadow-focused ion-beam technique to prepare multiple electron-beam-transparent cross-section specimens of ZnO nanospikes, via a procedure which could be readily extended to other anisotropic structures. In contrast with plan-view data of the same nanospikes, here the viewing direction allows the examination of defects without superposition. By this method, the coexistence of two twin configurations inside the wurtzite-type structure is observed, namely [2 {\overline 1} {\overline 1} 0]^{\rm W}/(0 1 {\overline 1} 1) and [2 {\overline 1} {\overline 1} 0]^{\rm W}/(0 1 {\overline 1} 3), which were not identified during the plan-view observations owing to superposition of the domains. The defect arrangement could be the result of coalescence twinning of crystalline nuclei formed on the partially molten Zn substrate during the flame-transport synthesis. Three-dimensional defect models of the twin interface structures have been derived and are correlated with the plan-view investigations by simulation.

Composition and structure of magnetic high-temperature-phase, stable Fe–Au core–shell nanoparticles with zero-valent bcc Fe core

“…An advancement in TEM preparation by Vieweg et al 20 allows site-specic sectioning via scanning electron microscopy (SEM) and FIB. 21,22 However, in the present case, the selection of nanostructures based on their ultrastructure, e.g. CS and NCS NPs, is only possible using TEM.…”

Local Strain Distribution in ZnO Microstructures Visualized with Scanning Nano X‐Ray Diffraction and Impact on Electrical Properties

“…ED pattern of a tilting series demonstrates that the ZnO rod exhibits a high crystal quality along the c axis showing strong diffraction patterns usually observed for a single component. However, ED patterns slightly tilted away from edge‐on zone‐axis observation conditions revealed multiple weak reflections which can indicate the presence of minor crystalline components [ 43 ] or can result from dynamical diffraction events in a thick specimen. See Figure S9, Supporting Information.…”