TEM based high resolution and low-dose scanning electron nanodiffraction technique for nanostructure imaging and analysis

Abstract

We report a high resolution and low-dose scanning electron nanodiffraction (SEND) technique for nanostructure analysis. The SEND patterns are recorded in a transmission electron microscope (TEM) using a low-brightness ∼2 nm electron beam with a LaB6 thermionic source obtained by a large demagnification of the condenser 1 lens. The diffraction pattern is directly recorded using a CCD camera optimized for low-dose imaging. A custom script was developed for calibration and automated data acquisition. The performance of low-dose SEND is evaluated using nanostructured Au as a test sample for the quality of diffraction patterns, sample stability and probe size. We demonstrate that our method provides an effective and robust way for recording diffraction patterns from nanometer-sized grains.

DLS and zeta potential – What they are and what they are not?

“…With image analysis softwares (e.g., ImageJ®) it is now possible to obtain size distributions of NPs from TEM images with information on mean size, standard deviation and overall estimation of PDI. However, such information from TEM images often do not corroborate well with DLS as DLS is an intensity-based technique [91] whereas TEM is a number-based one [92] making them fundamentally different. While the samples for DLS are solvated TEM works on dry samples under UHV (ultrahigh vacuum) conditions [93].…”

Lattice-Rotation Vortex at the Charged Monoclinic Domain Boundary in a Relaxor Ferroelectric Crystal

“…EF-SCBED was performed by scanning the focused electron probe over a selected area on a 15 x 15 grid, step size of 2nm, and through a post-column GIF energy window of 10eV. The shift and tilt of diffraction patterns during beam scanning were minimized and calibrated using a silicon single 5 crystal [34]. Following the procedures described in [32], the symmetry of PZN-8%PT was determined as monoclinic Pm, which agrees with the X-ray diffraction result [12].…”

Accurate Diffraction Peak Identification for Scanning Electron Nanodiffraction Based on Automated Image Processing and Feature Detection

“…By controlling the built-in TEM deflection coils with a DigitalMicrograph ® script, we can scan the nanobeam across desired sample area and acquire a series of diffraction patterns over a region of interest. This technique is called scanning electron nanodiffraction (SEND) [6,7]. Recently, 3D-SEND is developed as a new SEND-based technique to determine 3D morphologies and orientations of grains in nanocrystalline materials, which can work with chemically homogeneous samples with grains of different orientation [8], as well as chemically inhomogeneous samples.…”