The advancement and extensive use of spherical aberration (Cs) correction systems in TEM has significantly improved the spatial resolution of low to intermediate voltage (up to 300 kV) microscopes. The combination of TEMs and aberration correction systems allow new properties of materials to be discovered at the atomic scale.
Using the unprecedented resolution of these microscopes during in situ experiments will open the door for new discoveries when materials are subjected to external stimuli such as electric fields or high temperature. With the Protochips Fusion heating and electrical biasing system, which is developed to offer a stable and low-drift platform, high-resolution imaging can be performed at high temperatures.
The experiment discussed in this article demonstrates the ability of Fusion to realize the full resolution capability of a TEM at elevated temperatures.
The TEAM 0.5 TEM at the National Center for Electron Microscopy (NCEM) at the Lawrence Berkeley National Laboratory (LBNL) was used to conduct the experiment. The TEAM 0.5, is an FEI Titan that is equipped with a bright X-FEG electron source, a monochromator, and probe and image Cs correctors (CEOS).
The TEAM instrument can resolve to 0.5Å in traditional TEM mode. For this experiment, the instrument was operated at 300 kV. Gold was directly evaporated on an E-chip™, resulting in the formation of small gold nanoparticles directly on the device. Gold offers good scattering and contrast essential for the resolution tests.
The phase-contrast image of a gold nanoparticle at 600°C is presented in Figure 1A, showing the lattice fringes and the typical 5-fold faceting and twinning characteristics of gold nanoparticles. As can be seen in the Fast Fourier transform in Figure 1B, a resolution of 0.6 Å was achieved at 600°C. This value is close to the TEM resolution limit of 0.5Å, indicating that Fusion does not limit the TEM resolution even at this temperature.
Figure 1. Gold nanoparticle at 600°C with the corresponding FFT
The nanoparticles became highly dynamic when the temperature was increased from room temperature to 600°C during the study. The nanoparticles began to coalesce, facets altered, and defects in the material started to move. Thanks to the instrument’s stability, imaging, recording of real-time videos, and analysis of these events with extraordinary clarity became possible at the atomic scale.
Conventional and aberration corrected TEMs need a low drift and stable heating system to completely exploit their resolution capabilities for analytical and imaging analysis. The Fusion heating and electrical biasing system allows for atomic resolution imaging and analysis of materials, and is suitable for in situ heating of all materials.
This information has been sourced, reviewed and adapted from materials provided by Protochips.
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